End of the day the price for him is what we think he is worth, not anybody else15m seems reasonable
Lets not forget he is unproven at PL Level and no guarantee he would deliver consistently. It is much easier in the Championship primarily as you don't come up against sides like Man City where you cant even get the ball off them. I would expect Clarke to do well in the Prem relatively speaking but how much up side there is from 15m maybe 20-25 at most
Absolutely £20 million minimum for me. If other teams think its too much then they can do one