I have for sale an arcade for Xbox. It looks like it may have been (really well done) homemade. This is for the original Xbox and works well. With some modding, I'm sure it can be manipulated to work on other platforms too. It does show some signs of use, but overall looks great. It's pretty big...
I recently came across a PAL PS2 slim. I live in the US, so there's not much I could do with it. I was thinking about selling it so maybe someone could play some PAL exclusives on a non-modded system. Is there a market for them here? And would they be worth more or less than an NTSC PS2?
I've always had luck at flea markets and thrift shops. If you want a lot, you can also find lots on eBay where each game would cost less than a dollar, and you can resell the ones you don't want.