The Bhoys defender is currently generating talk of a possible switch to Emirates Stadium.
An initial approach of £15m ($19m) from the Gunners is said to have been knocked back, with that figure branded an “embarrassment” and “pittance”.
Bonner is among those who consider Tierney’s value to be considerably higher, with the Hoops legend also of the opinion that the Scotland international could be setting his sights above north London.
He told BBC Sport: "If Kieran was playing in England, he'd probably be worth about £50m.
"But because it's Scotland, I would think £25m would be a price you'd start talking about, with add-ons.
"He's got the ability to go into a club like Arsenal. Whether Arsenal is a big enough club for Kieran Tierney, that's the question.
"If you were picking out a player in British football at the moment that can play left-back, himself and [Liverpool's Scotland captain] Andy Robertson are the best two in Britain, if not Europe."
Bonner has a point when it comes to Tierney’s valuation.
He is just 22 years of age, but already has 170 club appearances and 12 caps for his country to his name.
With that in mind, he is considerably further along in his career that Aaron Wan-Bissaka is at Crystal Palace.
The Eagles full-back is, however, closing in on a £55m ($70m) transfer to Manchester United.
He is just a year younger than Tierney and is yet to grace the same kind of stage, with no Champions League or senior international experience of which to speak.
Bonner is right to suggest that players moving out of the Scottish Premiership tend to generate smaller fees.
Tierney, though, has been tipped for the top for some time.
Only his loyalty to the club he supported as a boy has kept him tied to terms at Parkhead.
Interest in his services is only likely to build from this point so if Arsenal do want to get a deal done, then they may need to raise the stakes and move swiftly in order to secure a prized signature.