Dev CD 2.1 comes with StormC 3.0 and PhxAss (which is free anyway). VBCC is a good choice for a free compiler. Much simpler to set up than gcc.
NDK 3.9 is still available free of charge from
http://www.amiga.com/3.9/download/NDK3.9.lha.
Combine that with GoldEd, VBCC, PhxAss, fd2pragma, and WinUAE, and you've got a pretty decent development environment. (I use Microsoft Visual Studio's IDE, Cygwin, and a gcc cross-compiler.)
Trev