My local retro shop has Rule of Rose creeping up toward $400 and Haunting Ground up at $200 now. I remember when both were going for around $80 several years back. This store is one that people make a point to visit when they come here, so I know their pricing is always current with going rates. I believe Jason from Giant Bomb went there and bought Panzer Dragoon Saga for $500 a year or two back.
Gravity Rush on PS4 is hard to find now and last time I checked, was nearing $100. Some of the Limited Run Games stuff seems to be up there too. The Shantae games are all up over $100 on both Switch and PS4.
I look forward to when Vita stuff is crazy expensive. I don't have a huge collection or anything, but I think the day will come when some of the better stuff on Vita that can be played on the TV units will end up being pricey.
Right now we seem to be entering the period where PS2, Gamecube, and OG Xbox stuff is sought after. I think PS1, N64, and Dreamcast stuff will stay around where its been for years, but I think everything that came after will start creeping up over the years. It'll be real interesting to see what happens if Sony says the PS5 will play all generations of discs. I think then we might really see some good jumps.