In an ideal world, this lens should go for about 75% of its real market value. But like the K f/1.2 on ebay the other day, all these untested, condition-unknown lenses are going for what a fully tested and accurately described one should go for.
I will probably put a sufficiently low bid on it (even though I want an even earlier model with the logo engraved in the front cap), but I can see it ending in the $500-550 area. If it doesn't hit $500, I'll be surprised...and in that case, I may also be the next owner