You can use XNA (C# and DirectX) which allows you to publish to the Indie store. If your game looks good enough, you apply and they think it will make enough money they might publish it onto the Live Arcade store.
Although UDK does not currently support consoles the engine does. If you made a game, impressed an MS rep enough to get accepted (and therefore get a devkit) you could probably sort out some type of license with Epic. (This is a guess, but they say they are happy to discuss full licenses with UDK users in the FAQ).
I've always considered Unity an indie engine personally. Don't they have limitations that you can't have major publisher support for the license, or is it just 1200 no matter what?
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