It's a ridiculous argument, first of all that $5 would deter anyone, secondly the clang/llvm binaries are available freely, which is the default compiler in Xcode. http://llvm.org/releases/download.html#2.8 GCC is freely available in source form.
As far as I observed in my coworker Macbook gcc still is the default compiler in Xcode 4. Just compiled some software with it today, and it pops a lot of gcc's in ps aux.