Boss Paul Lambert believes would be suitors would have to pay double what Aston Villa paid for striker Christian Benteke.
"When the guy came into Villa, people were saying to me 'who is he and why are you going for someone from Genk?"' Lambert said.
"With what he's done, he's a cult hero already.
"He's only 22 and he's got years and years ahead of him. He's not at his peak, but what he's done for me and for the club is fantastic.
"If someone wanted to buy Christian, they'd better have a few quid in their pocket."
Asked whether Benteke's performances have doubled his value since last summer, Lambert replied: "Yes, by miles.
"He's not just going to walk out of here for the value he came for, that's for sure.
"We have given him the opportunity to show what he can do and I think he is loving his football at the moment."