The source is messy and compiler-specific, and many implementations are irrelevant to modern systems. For example, I recall Chapter 14 is about implementing multiplayer over serial cable by directly writing to I/O ports in assembly language to drive the UART. I never did get that to work, but trying to translate the book from the Watcom C + MASM toolchain to the QBASIC + DEBUG toolchain -- without access to a working copy of the former and zero prior C experience! -- actually taught me a lot.
So maybe there is a reason toolchains should be expensive -- to encourage starving students with lots of time but little money to expand their minds by jury-rigging alternatives :)
[1] http://www.amazon.com/Tricks-Game-Programming-Gurus-Andre-La...
It might interest you to know that according to http://en.wikipedia.org/wiki/DJGPP, there's been a DOS port of gcc since 1989.
Google Play, as far as I'm aware, don't do this for every country you sell in. Leading to situations where you may be liable for tax payments but won't know it unless you do the research yourself. This is discussed in more detail here: http://retrodreamer.com/blog/2012/03/why-dont-we-have-paid-v...
Actually it is 25$ once and for all.