Buy Broken Xbox 360, Send to Microsoft, Sell on Ebay?

Do you think anybody buys Xbox 360s with red rings on eBay for like $30, sends it to Microsoft to fix for free, then sell them for like $100 on eBay again? I don't see any faults with this plan. Is there a limit that Microsoft gives you on how many they will fix?

Suggestion:

well my warranty fo my xbox expired but i called sent it in and they didnt charged me NEthing….so your plan seems legit…
1. buy red-ring xbox
2. send in to microsoft
3. ???
4. profit