Actually, I got some good C courses with KDevelop (which is free) and there are some very good ones online (for free).
That makes the total cost about $0.10 (or so) to $100 or so (depending on your connection, how you get Linux, how you get the docs etc (If I were to download Linux, it's not free - the phone company will be pleased though)).
Of course, you COULD leech those files of a friend's PC, with one of their UTP cables, which will reduce cost even further (well, there's always electricity

)