I'd add the Seecamps made by Larry to that group and the HK P7
Definitely! The Seecamp models have been desired collectibles for some time. My guess is that they've appreciated may be a couple hundred dollars over the past few years. You used to be able to find them selling in the $500 range; sometimes less.
I have always wanted a P7M13 - it's my nemesis gun. I've bid on many; won none - it always seems to go for a couple hundred more than my highest bid. And, now they are in the 3k range. Too rich for me....I'm out. Even the M8's are out of range for what I'd pay. If you just have to have one, perhaps the PSP's are still a reasonable value.