Comment Some Options (Score 2) 128
There are a few free options available, by free I mean as in beer.
For 8 bit work, you can go with Atmel ATMega and ATTiny, using the free AVRStudio.
Theres also MPLAB IDE for PIC micros, also free.
For 16/32 bit work, you cant go past ARM. You have Eclipse and CooCox as options for free IDE's ( coocox is more integrated, and has open source hardware debuggers available that can be easily used). Both are based on GCC toolchain.
Id recommend the ARM route, as the Cortex M series is very good for the price ( esp the LPC1700 series from NXP ), and the programmer and debugging tools are cheap and non proprietary.
Im sure there are other options out there too.