Where do you buy your gaming 'stuff'?

[Beware of Cuccos]

I can find games no problems, but i'm having a hard time finding other things. I'll be buying my first house soon. Going for a three bedroom. It's just going to be me (and probably a bunch of cats I will no doubt get to fill the void) and I would like to make the other rooms into a music room, and a gaming/movie room. I want to find some good posters for some of my favorite games- Ocarina of Time, A Link to the Past, and The Sims. Maybe even some Banjo-Kazooie stuff. I'm also looking for some set-around decor, figurines and such. I just have no idea where to start, and I don't always trust eBay or Etsy.