Dembele, 20, is enjoying a prolific campaign in Scotland, scoring 15 goals in 24 league games for the runaway leaders.
But it will take a massive bid to secure Dembele from Celtic, team-mate Gamboa said.
"I'd give you £50m for him, but I don't have the money," he said, via the Daily Express.
"He is a good player. He can go wherever he wants. We enjoy having him here and hope we can enjoy having him for a long time.
"He can go to Real Madrid or wherever he wants. He is a top-class player. The age he is, just 20, means there is a lot that he still has to do.
"But he is having a really good season for Celtic. It is good for Celtic and it is good for us as a group. We enjoy it."
Dembele struck a brace in his most recent outing, a 2-0 win over Hamilton Academical, to take his tally to nine in his past four games.
Gamboa, a 52-time Costa Rica international, said there was plenty more to come from Dembele.
"Just imagine what he's going to be like when he's 25 when he is a more mature player and he has more experience," he said.
"He is a strong player and he shows everyone that in training all the time. I wish the best for him. But we enjoy him just now.
"He may go to another club, but just now he is here until at least the end of the season so we should enjoy his football and his goals."