I somehow lucked out today, and purchased a pair in mint condition for about $300 CDN, which is the lowest price I've seen them go for. No shipping or anything, and the money went to help a university student who had already been bit by the headphone bug.
Impressions, so far these are giving me spine chills, and thats never happened to me from any headset (well, I've never owned anything of this quality before). Early impressions is that the sound signature of these are perfect for my listening, and music production. I will say that I may still hold on to my Denon AH-D600 (for its incredible comfort, lovely low end, and friendly sig). Will figure that out later.
I've been looking to get the HD-650 forever and ever, and wanting to have a benchmark for this audio journey, and listen to a classic. Going to need a better amp I think.