Peterborough chairman Darragh MacAnthony has warned Joe Lewis' suitors that they will have to raise their bids significantly.
Posh claim to have rejected three bids for the England Under-21 international goalkeeper, who has handed in a transfer request.
MacAnthony told talkSPORT: "He's 6ft 7ins, he's played over 200 games and he's been in the England squad.
"I invested heavily in Joe Lewis and if Premier League clubs have ambition and want to buy the best English talent out there they have to do the same and pay the money.
"I can't hold him back but let's not forget no-one had heard of Joe Lewis until Peterborough bought him.
"I took a chance on him and I will not sell him for the same fee I paid."