For me, the most fun part about being a retro gamer is the shopping. Something about the “thrill of the hunt” make hobbies such as this extra enjoyable.
Press The Buttons has a wonderful writeup, Acquisition: The Art Of Purchasing Used Video Games in which several tips and ideas are offered on how to aquire new pieces for your collection
I’m surprised I didn’t come up with this article first, but I think this page is better written than I could have done.
I also want to commend Press The Buttons for being featured on Slashdot’s main page. 😀