Sig GSR price check?

Hey guys,

I was browsing one of the local gun/pawn shops this afternoon when I noticed a used stainless GSR sitting in the case. It is almost identical to this one, except that is has "Revolution" etched/engraved below the ejection port:
http://www.emeraldvalleyarmory.com/store/media/Sig/Sig%201911%2045%20S.R.6B.jpg

The sales guy said that it was used, but unfired, and a quick glance at the chamber supports that. However, I noticed what looked some corrosion on the frame (either side of the grip safety, as well as near the trigger on the right side, so it's probably from sweat that was not cleaned off?). I wish I had taken a picture, but it looked like black "grime", but wouldn't scrape off with a fingernail. They wanted $850 OTD, as they had been sitting on it for a while (tag said $950), but I feel like that's a little high, given the condition; what do you guys think? Also, do you think that the corrosion could be removed without need to refinish the frame, and what would be the best way to go about doing so? Thanks!

Bud's has a new one available for $844 delivered, take in a copy of their web page and try to get a better price. http://www.budsgunshop.com/catalog/product_info.php/products_id/50943

If the gun in question is exactly like the one pictured, you don't want it anyway, especially with so little price difference from a new one. The "manhole cover" in the slide was one of the parts that flew out of mine, along with the firing pin safety parts that it retains/accesses. (Revolution Carry, 2007) They no longer use this design.

Did it look like this?

http://img.geocaching.com/user/2a108391-6b14-4827-b3ae-4e501966af98.jpg