STM32 + STlink V2 Clone (or one included on Discovery and Nucleo series of boards) + CooCox CoIDE is I think the closest you will get for free, that resembles a commercial toolchain.
It's generally the same thing as "frankenstein" toolchains (editor, gcc, gdb, openocd, zlin CDT and so on), but all the stuff is already done and configured (CoIDE is a proprietary modified compilation of Eclipse), you only need to install the GCC and provide path to it in the IDE. It has some code generation tools, libraries and so on.