Well, I didn't sell, but I had an offer from Barcelona for my regen striker - 82 million.
Luckily, the finances are great at the club, so the chairman left the decision to me, and I won't sell him, as he's one of the top-ten strikers in the game by now and at 22 has still a lot to do at my club.
In the same save, I've seen Pato get sold (dunno where) for 92 million.
(all fees in Euro, not pound)