The Dutch side eliminated two continental giants en route to the Champions League semis, but how does their squad value compare to Europe's big guns?
Ajax this week will take on Tottenham in their first Champions League semi-final for 22 years, with a place in their first final since 1996 a real possibility.
There are endless stats that emphasise how great an achievement it is for the Dutch side, who hadn't reached the knockout rounds of the competition since 2005-06 before this season, but few stress the point stronger than the cost of Erik ten Hag's squad.
Using initial transfer fees only, Goal has calculated the total cost of Ajax’s 25-man Champions League squad before doing the same for the other biggest sides in this season’s competition, including the likes of Real Madrid, Juventus and Manchester United.
PSG | €718m
With PSG possessing the two most expensive footballers of all time, it's no shock to see them at the top of this list.
Below Neymar (€222 million) and Kylian Mbappe (€145m), the likes of Edinson Cavani (€64m), Thiago Silva (€42m) and Leandro Paredes (€40m) help this 25-man squad rack up an incredible initial cost of €718m (£621m/$805m).
The French outfit do have the most youth products in their 25-man squad of any team on this list, with Alphonse Areola, Sebastien Cibois, Presnel Kimpembe, Christopher Nkunku and Adrien Rabiot all having come through the ranks at the Parc de Princes.
However, despite a spend of €1 billion coming on top of that since Qatar Sports Investments purchased the club in 2012, three successive last 16 exits mean PSG are nowhere near their dream of winning the Champions League.
Manchester City | €682m
Manchester City's consistency in spending sees them come second in this list, with 12 of their 25-man squad commanding fees of €35 million or more.
That takes the total cost of their squad up to a healthy €682m (£590m/$764m), with fringe player Riyad Mahrez the most expensive purchase (excluding add-ons) after his €69m move from Leicester City last summer.
Their defence is the most expensive area, with their most common back four in the Champions League this season costing a combined €187m.
However, even all that money could not stop them leaking three goals at home in the second leg of this season's quarter-final tie against Tottenham.
Manchester United | €661m
Manchester United's comeback against PSG sparked the potential of a story for the football romantics, with club legend Ole Gunnar Solskjaer having the chance to replicate his heroics in 1999 as a player by guiding them to the Champions League title as a manager.
But the romance of that story - before it was destroyed by Lionel Messi's Barcelona in the quarter-finals - was not so dreamy once you analysed the figures.
The club's current crop of players have cost an incredible total of €661 million (£572.5m/$740.8m) - €189.9m of that on Paul Pogba and Romelu Lukaku alone - despite United having featured in the Champions League knockout stages just once in the last four years.
With €160.6m splashed on players who have played less than half of their games in Europe this term, it's clear the 2007-08 winners will have to spend more effectively if they want to rediscover past glories.
Liverpool | €594m
After Loris Karius' error-plagued performance in last season's Champions League final, it was no surprise that Liverpool splashed out €75 million on goalkeeper Alisson in the summer.
Add his arrival to Virgil van Dijk's last January, and you have a €161.5m defensive duo - albeit, an important and necessary pair that Jurgen Klopp needed to purchase.
The squad he has built has certainly come at some price, with the recent midfield additions of Naby Keita (€61m) and Fabinho (€46m) taking the total cost of Liverpool's Champions League squad up to a whopping €593.5m (£514.75m/$668.15m).
But Klopp has addressed the areas that needed improvement and, if the money spent can help the Reds go one better than last year - both in the Premier League and in Europe - it will certainly be worth it.
Barcelona | €573m
Despite rivals Real Madrid having a bigger reputation for spending, Barcelona beat them on this list with their squad value of €573 million (£497m/$645m).
The nine-figure sums paid for Philippe Coutinho (€120m) and Ousmane Dembele (€105m) account for almost 40 per cent of that total, which is an alarming statistic given that both attackers have underwhelmed for large spells at Camp Nou.
Yet the bargain fees paid for the likes of Jordi Alba (€14m), Gerard Pique (€6m) and Marc-Andre Ter Stegen (€12m) help to bring the cost down, as does the fact that their most valuable asset, Lionel Messi, came through the youth ranks.
Given that only one side above them on this list is also in the last four of this season's Champions League, their spending is certainly no crime.
However, with many of their most expensive arrivals coming in the four years since they last won a European title, they will hope to end that barren run this year - especially with them firmly the favourites of the teams remaining.
Real Madrid | €475m
Real Madrid's incredible spending under Florentino Perez has not only earned them five Champions League titles during his time as president, but also the nickname of 'the Galaticos' for all their expensive marquee signings.
However, the departure of Cristiano Ronaldo and a dramatic reduction of that spending in recent years means the reigning European champions have fallen significantly behind the continent's elite on the market - with this season's squad costing a surprisingly low total of €475 million (£412m/$535m).
Gareth Bale (€100m), a player reportedly on his way out, is the most expensive player on their books, some way ahead of Vinicius Jr (€46m) in second, who himself only arrived at the Bernabeu in the summer.
Still, Madrid spent €151m in the summer and, with their resources, quality and experience, they should not be crashing out of the Champions League in the last 16.
Juventus | €424m
Despite the €100 million addition of Cristiano Ronaldo in the summer, Juventusrank well below most of Europe's elite for spending, with their current squad amassing a total of just €424m (£367m/$476m).
Yet, with the recently crowned Italian champions boasting an ageing squad, that comes as little surprise. The likes of Martin Caceres (€600,000), Andrea Barzagli (€300,000), Leonardo Bonucci (returning for free in a swap deal) and Blaise Matuidi (€20m) all arrived in Turin after their 30th birthday, making deals much cheaper for Juventus to complete.
Joao Cancelo (€40.4m) and Federico Bernardeschi (€40m) are the club's most expensive arrivals after Ronaldo, but only started five and six of their 10 Champions League fixtures respectively - as well as 19 and 12 of their 33 Serie A games.
Without investing in improving their starting XI, Juventus' obsession of winning the Champions League can only remain a pipedream.
Bayern Munich | €354m
Bayern Munich's ability to do shrewd business sees them sit very low down this list, with a total squad cost of just €354 million (£306m/$397m).
Star man Robert Lewandowski arrived at the club for free, the versatile Joshua Kimmich cost as little as €7m and veteran Thomas Muller came through the club's youth ranks.
With nine of their 25-man Champions League squad over the age of 30, the club will have to spend in the near future in order to replace those soon to retire or move on.
But given they have spent €240m less than Liverpool, the side that knocked them out in this year's last 16, there should be no great surprise at their performances this season.
Tottenham | €313m
After Tottenham made history by becoming the first Premier League club not to make a single signing in back-to-back transfer windows, their lowly place on this list, and the difference in their spending compared to Ajax, is no shock.
Yet, their squad still cost €313 million (£270m/$350m) - a total which is not far behind Bayern Munich.
The price tags of Moussa Sissoko (€34.6m), Erik Lamela (€29.8m) and Lucas Moura (€28.9m) are most responsible for this figure, but even then their fees are very little in football's post-Neymar economy.
Key men like Christian Eriksen (€12.7m), Kieran Trippier (€4m) and Danny Rose (€1.2m) all arrived for incredible bargains, while Harry Kane, who would be their most valuable asset, came through the club's academy.
Ajax are certainly the story of this Champions League season, but Mauricio Pochettino deserves great credit for guiding Tottenham to the last four on his budget - especially given they overcame big spenders Man City in the quarter-finals.
Ajax | €95m
It's absolutely no surprise to see Ajax at the very bottom of this list - but the margin by which they are may come as a shock.
The Dutch side's Champions League squad cost them just €95 million (£82m/$107m), with many of their key players costing little to nothing - or, in many cases, nothing at all.
Lasse Schone and Klaas-Jan Huntleaar arrived for free, while Matthijs de Ligt, Donny van de Beek and Noussair Mazraoui, among others, do not even need to be registered in Ajax’s main Champions League squad as they are home-grown players born after January 1 1997 who came through the club’s academy.
Goalkeeper Andre Onana and forward Kasper Dolberg arrived for just a few hundred thousand Euros each, but most remarkable of all is Frenkie de Jong's cost - which was, symbolically, just €1.
It's the likes of Daley Blind (€16m) and Dusan Tadic (€11.4m) who make up most of the squad's total cost, after they were recruited by Marc Overmars and his team in order to add experience to this youthful yet talented crop of players.
On an individual basis, one could regard their signings as deals where Ajax have overpaid. But the bigger picture shows that this history-making side has been constructed for an incredibly small price.
At €95m, Ajax cost more than five times less to put together than Barcelona and Liverpool, six times less than both Manchester clubs and seven times less than PSG. This makes their Champions League journey all the more remarkable.