I saw a seller on Etsy that had a lot of repro carts, including a few that were officially "cancelled" prior to release, but haven't picked any up yet. I was thinking about trying Fido Dido for the Genesis, because the game was apparently finished...despite never being officially sold.
Missed out on scoring some from Timewalk Games before they shut down.
These made it in to my collection shortly afterward: Burning Heroes - Haven't played this one yet. Mystic Ark - Started but got shelved due to other things. Secret of Mana 2 - Blew a lot of time on this, got stuck, used an Action Replay and not only did it fail to boot with the game but it wiped all my saves. Terranigma - excellent game!
My son got me the red 150 in 1 for the nes for fathers day. Some of the games are the Japanese version but the cartridge as a whole works great. I even play it on my nes to snes adapter. Awesome gift, and I think it was only like 30 bucks.