best lga 775 cpu?

Amazon's processor is still brand new, the one on ebay is used, hence the price difference. But honestly I wouldn't pay near that much for anything that old, that's why I also talked about the Q9550 which is only a little slower and is still capable and at least mine is easily overclockable.
 
Agreed. I mean, hell, you could buy two or three complete systems that can outdo what that new-in-box processor can do.

Unless they're becoming collector's items or something. Maybe they just didn't want to ever lower the price from what they went for when they first came out. Sheesh.

(side note: I happen to have an old Dell 630i myself with a Q9550 that I picked up recently. Nice little system, though it's all the original hardware from 2009, thus, pretty dated. I basically just play around with it, but it's not my main system)