Right now they are running between 600 and 690(ish) new. Online prices appear cheaper, but that is only before you factor in shipping and transfer cost. I believe Bradis had the S12s on sale for 630(ish) last week.
Used, that's a whole new ball game. The S12 has seen some very extreme price swings (from sub-400 to 900+), due to both ATF and Importer scares. That means people selling their used models often aren't being realistic about current value. I.E. They PAID 900 for theirs, so you should pay them that as well!!! Also, finding an S12 owner that hasn't converted theirs is pretty rare. So a lot of the used models will have had work invested into them - which of course makes the owner believe the gun is worth it's weight in gold...
I'd almost tell you not to waste your time looking for a virgin used model. Just find the best deal on a new one that you can.
well i was wondering because i have really been looking for one and the shop here has a couple but I thought they were priced a bit high the used one was 699 and it was fully stock and i remembered seen them online new for 599 so i thought i would ask
the cheapest they've been was $499 3 months ago at classic arms, however you don't get a side rail or metal thread protector and they have the "stippling" where they removed the original importer markings. They sold out instantly. Now they've bumped their prices up to $550 which is still cheaper than they've been. Keep in mind, as JAG says, you still have to pay for air shipping and a transfer fee, so bradis may be your best bet.