One thing about this process that isn't mentioned until later in the article: You need a Mac to build a Mac (Hack) like this. That is, you already have to have a Mac to be able to perform some of the installation steps described.
How to build a Mac "Hackintosh" - Great price
That limitation aside, I agree with the author: You get an awful lot of performance for $900. The system built here is close to a $2,500 Mac Pro, with a few tradeoffs for either system. (The Hack Pro has more RAM and a bigger hard drive, while the Mac Pro processor is better, and it has DDR3 RAM.)
As for the part where this article tells you how to do something that is illegal, one of the commenters makes a really nice point:
I'm not much into violating the laws these days, but this article sure makes a real Mac Pro look very expensive. (And I write that as the owner of someone who has bought several iMac and MacBook/MacBook Pro systems ... and will continue to do so for the foreseeable future.)