I have a couple of old FIE Titan .25's that were made and/or designed by Tangfolio. I see them lots of them on gunbroker. One of mine is actually a nice working gun...and it only cost me $139. The other cost almost $100 less, but doesn't work as smoothly, though it does work and seems to cycle ammo fine. I think Phoenix Arms made .25's up until just recently, so new ones are probably still out there, too.
.25 is a loser for self defense, though, unless it's carried as a backup to something else. The .32 is better. (Check out CZ-70's as others have mentioned, or the earlier CZ 50.) But for self defense, why settle for that, either, when better options are readily available?
CDW4ME mentioned the pocket .380's. As luck would have it, both Ruger AND Taurus are both adding new .380 pocket pistols to their line...which means that their previous models - the Ruger LCP and the Taurus TCP - have been showing up a lot lately at extremely low prices (because they're being phased out.) Low prices as in under $200 for brand new guns! I have a Ruger LCP in my pocket right now and it's a gun I trust very much. I had one problem, but Ruger took care of it pronto! I paid $309 for mine new a few years ago, and it was a good value even at that price.
But if your main point is to collect, then the old Titans and the old CZ's are great options, though the CZ's are too big to really be called pocket pistols. Good luck.