Anyone who has ever spoken to him or even heard him in an interview could tell you that's not true at all. He doesn't have a bad attitude; he's desperate to succeed and works very hard in order to do so.
He signed for United far too early; he wasn't half the player he is now, and he wasn't...
As pointed out already, Bolasie went for over 30m and Wilf is a far superior player. Gylfi Sigurdsson left Swansea for 45m.
Considering the fact that he has only recently signed a new contract and the crazy state of the transfer market, I'd imagine he'd go for somewhere in the region of 50m-60m.