I currently do not own expensive/over priced games, but if you do post them down :)
I've got a lot that are at or above their original price but I'd say my most valuable ones are Rule of Rose and the Misadventures of Tron Bonne.
I've had tons of Neo Geo AES, Sega Saturn, and TG16 games that'd be worth a fortune now that I picked up reasonably and made a small profit off of that I wish I still had.
I have all of the .hack games on PS2 (4 original series and the 3 GU games) and they fetch a pretty penny themselves. I also have all 3 Xenosaga games, the first two aren't worth much but the third goes for quite a bit (like $70-80 I think).
Not really worth a lot but I am very proud of my Digimon game collection. I have a copy of every US released Digimon game. :3
Without intending to, I do have a lot of expensive and over priced games. I purchased my games when they "were" the console on the shelf. Their hey day. Many of the games I own if I had to purchase them now I just wouldn't be able to. I own everything from NES to Xbox one. I own many handhelds from each era.
I have one or two of the .hack games on PS2. And I do have the Xenosaga series. I have Guardian Heroes for the Saturn, Bangai-O for the N64. A lot of the SNES games that are now at unreal prices. Gun Nac on the NES is at unreal prices, so glad I picked that up when I did, I love that game. Crisis Force is the same way, another great shooter on the NES, Famicom. I have the Lunar series complete for the PS1. So glad I purchased those long ago from then what was called Babages. I have a lot of those old RPGs that seem to hold their price and then some. Games on my Turbo Grafx, NES, N64, Saturn, Dreamcast, Genesis, SNES, PS1, PS2, etc, it seems that each generation has its must have game. Collectors have pushed the prices out of the reach of the average gamer.
(https://i.imgur.com/wtm76qZ.jpg)