I've haggled on price utilizing the private message system on GB before - I'd consider that more of a fluke though. Most people won't even answer or will immediately decline.
+1 on the AP5. If you do get one, check the ejection when you shoot it. My ejector lever was slightly out of spec and it led to FTEs. I replaced it with an HK lever and it's been flawless ever since.
What happened at GCG? Curious.
Grey Man is a nice shop overall but I've had hot and cold experiences there. I need to get out to the Outpost, seems like a cool place.
I've wanted a USP Tactical in .45 since forever. I've seen a few around but circumstances never seemed to align for me to pick one up. I did manage to get a standard .45 and kept it for a little while but it wasn't truly what I wanted.