Hope I'm not stepping on any toes, but I was the original owner of this lens and thought I would chime in.
1st - If I had the money I would buy it back, this lens is awesome, and I do regret selling it. :/
2nd - Frostugh is a stand-up guy, you should have no reservations buying from him, my transaction with him when he bought the lens was great.
3rd - IMHO His price is very fair, I would buy it if I had the money, dang - why don't I have the money.
4th - Here is one of my favorite pictures, taken
with this very lens. Did I mention I would buy it back if I had money.....