If the seller paid retail for that stuff, he likely lost money on the deal after Ebay/Paypal fees.

I think it all depends on the demand for what your selling to them, it's all about timing. I traded in a Gamecube, 2 controllers, and like 8 decent games (all of which I bought used at Gamestop for $20 or less) on Gamecube like a year after the 360 was released and they gave me enough to get a brand new Xbox 360 Pro, a year of Xbox Live and Call of Duty 4. And the employee at Gamestop told me I chose the perfect time to trade it in because if i brought all that in like a week later it would have been worth about half because they were about to do a massive sale on the last gen consoles and games.

JayQproductions

You have to be leaving something out. A new 360 pro at that time cost $300-$400 alone. There's no way they gave you that much credit for a Gamecube and 8 cheap games.

Best Buy is giving a $75 gift card if you buy a 250gb slim this week.

There's no reason to shop at Gamestop unless you like paying full MSRP for pretty much everything they sell. Not to mention the used crap they want way too much for. Shop around, there are almost always game deals to be found elsewhere.

TRU does not price match other retailers. As has been said, you would have to return it and buy another system at Best Buy.