I'm really disappointed to hear all the suggestions of making a 3rd-party (retailer) eat the cost of something that's MS' fault. "Tricking" Gamestop or Target or Walmart, etc. into exchanging a damaged disc is unethical.
I would contact the game publisher and see if they have a scratched-disc replacement policy. You might end up paying shipping to send the scratched disc back, but many publishers will do this for a minimal fee, perhaps $5-10. You can also contact the customer care center of the retailer where the game was originally purchased... sometimes they will help out. Below is something that happened to me.
I purchased an XboxLive 13-month Gold account card from Best Buy, went home, and activated the account. Unfortunately, I activated it under the wrong profile. So I contacted MS and asked how I could switch it to the correct profile. The long and short of it is that MS will not allow activated Gold accounts to be switched. Period. Even if you haven't used it for 1 second. That's a crap policy, but I digress.
So in desperation I called Best Buy Customer Care... not the local customer service at a store, but their corporate Customer Care office. The girl was very sympathetic but said they couldn't give a refund for the card since the account had been activated. She also said that the MS policy wasn't customer friendly, and then offered to meet me half-way... she sent a $25 gift card as a customer-good-will gesture to help with half the cost of purchasing another $50 Gold account card from Best Buy. Yeah, I only recovered half the cost, but at least I wasn't out the full $50.
This illustrates why I hate the loss of small, independent, mom and pop stores... the kind of service Best Buy provided isn't typically found in the large chains.
