Where are you guys seeing them at these prices? Locally, they are asking $750 used when you can find one and about $900 new with night sights. I did a quick run through Gunbroker and didn't see much in the $600 range.
In my experience local shops nearly always charge more than online. They have to charge more due to overhead plus they probably order fewer guns thus getting worse deals from the distributor. I just checked and they are currently $788, but around Thanksgiving Bud's Gunshop had new USP 40's for just under $700 if I remember correctly.