That is the opinion of former Rangers and Scotland striker Kris Boyd.
Arsenal have already had multiple offers for Tierney turned down by Celtic.
A £15m bid was rejected earlier this month which led to the Gunners returning with a £25m offer over the weekend.
However, Celtic were said to be unhappy with the structure of payment Arsenal were proposing, with only £18m being paid up front.
“When the numbers are getting to the stage that they’re getting to, I know that Celtic will look at the English market and say ‘the players are going for…’, well I think they already said ‘Wan-Bissaka for £50m’,” Boyd told Sky Sports News.
“But we all know the English market is inflated right now.
“Whether it continues is a different story.
“When you see Kieran Tierney there is no doubt there is a talented footballer there.
“But I can’t see Celtic getting getting that type of money for him.
“I think if you’re getting towards the £20m-25m, then you’ve got to sell him.
“I think Celtic can be proud of what they’ve done, given him the opportunity to play at that level.”