Harvin is a special player; however, I think his injury history has to come into play.
Megatron is elite! I can't imagine another WR getting that kind of money.
I've always thought Fitzgerald was overhyped and overpaid. Just because the Cards made a mistake doesn't mean other teams should do the same.
IMO Harvin should probably be paid near what Bowe received. Not because of his receiving prowess but because of his ability to run the ball and do KR. Most likely though, if he gets a big contract they won't want to risk injury with the KR and he would just be a WR or getting balls out of the backfield dramatically decreasing his impact on the game.