Tokina 11-16mm f2.8??? price??

Hey guys! I've been hunting for one of these lenses for a while now. I found one that looks to be in good condition. The guy is asking $525 for it. It is version 1. Is this a good price for a used one? What could I offer him?
Thanks!

I think its fair, if its in good condition.

Thanks John!

Awesome lens. Worth every cent of $525, but the bargain hunter in me would offer him $500 cash!