So you want to get a compiler for free that you can use to make and sell programs?
As far as I know gcc supports 64-bits and the executables can be given away freely without needing the code to be GPL'd. Executable code produced by the compiler doesn't constitute a derivative work.
Alternatively the Visual Studio compilers can be downloaded for free; it's only the IDE itself that is expensive. I believe they can then be used in an OSS IDE such as Eclipse.