I've got a few...
Like the OP mentioned... the HK P7. I had a chance about 15 years ago, when those demilled German police issue P7's rolled through, but at the time, $600 was too much. Now it seems like a bargain.
A Dan Wesson Pistol Pac, particularly in .41MAG, but maybe one in .22LR to go with it.
Ithaca 37
AutoMag
HK 91 or 93, MP5, or versions thereof
M1 Carbine.
Belgian HiPower
Bren 10
I know a lot of those are available on the used market, but the prices are just ridiculous. Even things like a nice, clean M1 Carbine are stupid.
There are a few firearms that aren't on that list... because I owned them but stupidly sold them, so they are in a different category.