Mostly, I buy new, sealed, video games for my son. Games that are pretty newly released sell for $50, plus $3.00 tax. I can get that same game on release day for $40 including shipping. After awhile, the new release titles are reduced in price and I can some on eBay for $20 to $25 (shipped) and the same game is still $50 in the store. I've never been ripped off (knocking wood) and I've only got the best things to say about the most of the people I've had contact with thru the years.
I also buy a lot of DVD's this way. Always new and sealed. It's getting more difficult though because so many are imports from Asia and I'm not interested in those.
I don't sell a lot, but I have sold a few things. It was years ago and I forget how much I paid for the Hooked on Phonics program, but I'd guess from $200 to $300. My son has a learning disability, so I thought it would work. I liked the program, but if you didn't get this step completely, you weren't suppose to move on. So, we'd spend lots of time covering the same thing over, and over, and over, and over. It was just too tedious and wasn't working. I sold it on eBay (partly used, but much of it new) for about $10 less than what I paid for it. Like I said, today I can't remember the exact amounts, but I can remember how excited I was back then! I'll take that to just giving it away. I do that most of the time though.