I got mine for $600, and they were brand new, never installed (but had some paint chips), and they didn't include rotors (didn't care, cuz I already had some). That was on eBay. Most of the time I see these on the forums, people want $850 or more for them. Truthfully, $750 is a pretty low price, comparatively. It never hurts to offer less though. I might start at $650 and see what they say. If you can get them for $700, that would be a pretty good deal.
BTW, you'd have to get new wheels if you want to use those...they won't work with the speedstar wheels.