Dave Dunfield's Micro C is available for $90 and it is a good choice for small to medium projects with low real time requirements.
It comes with all the libraries as source. No B.S. Worth the $$ !!

I recently purchased TASKING C51 and returned it since frequent compiler crashes made work virtually impossible. They also have a strange way of philosophy in their code....


IAR (www.iar.com) systems also offer a development system.

After going thru all the demo stuff
KEIL is the most straightforward solution if You feel like paying for it.

IF You go low cost also have a look at Sendeep Dutta'S SLDC freeware compiler.
Not so bad !! All you have to do is browse around for library sources at BSD's.. --and build your own libs but that should not be too much of a problem.

Good luck

Jan