I remember picking up a Yugo SKS from AIM for $130- cleaned up real nice. I paid $85 locally for a '38 (IIRC) Mosin- great shooter. Those deals are long gone now!
Recently picked up my first cop trade-in HK pistol from Summit, which was also my first .40S&W handgun, and was very impressed- I am at about 80% that it was never fired after leaving the factory. I think I paid around $400 for the gun w/box so when I see 'used' USPs selling for $700 or more I get a happy feeling inside.
There are some good deals out there. Right now I'm picking up some lowers before the new laws in July, but I hate to see the good deals pass me by!
EDIT to add: I remember back in 2005ish there was a dealer in Lakewood that had several P7s that looked really nice; he was asking $900 but I felt like it was too much. Oddly, as much as I would LOVE to own one, I still don't think they're $900 guns. So no regrets other than I know I could get almost double for it now- but my firearms purchases tend to be steered towards 'utility' - in other words, the gun must fill a gap somewhere and be useful. I don't own safe queens or investment guns. Too many other competing interests/hobbies.