My collection isn't *quite* as impressive as most of them here, hahaha.
NES games: Dragon Warrior IV (I rented the other three from Erol's waaay back in the day)
PS1 games: Dragon Warrior VII
PS2 games: Dragon Quest VIII: JotCK
GBC games: Dragon Warrior Monsters, Dragon Warrior I&II, Dragon Warrior III
DS games: Dragon Quest IV: CotC, Dragon Quest V: HotHB, Dragon Quest VI: RoR, Dragon Quest IX: SotSS, Dragon Quest Heroes: Rocket Slime
Dragon Quest Sofubi Monsters: Slime, Golem, Slime Knight, King Slime, Metal Slime, Metal King Slime, Slime Stack, Liquid Metal Slime, Great Dragon, Orochi.
I started collecting the sofubi monsters about a month ago. I get them at mostly-reasonable prices from amiami.jp and I hope to have the full set by the end of the year. Right now I'm just looking for ones that cost under $15 US aren't on back order, but eventually to get some of the rare ones I'll have to resort to more expensive means. Dunno if I'll even try to get those metallic bosses or large-sized monsters.