they are very easy to build, and i have done it myself...bought all the parts at
www.mwave.com. They are very reasonable on price...The machine you can build yourself will be a beast compared to what you will spend on a prebuilt machine. However, the lesson i learned after building my beast and having it for 4+ years is that Apple is revolutionizing the industry and i bought a mac. The hardware and software works seamlessly and it has great security and stablity because it is built on unix....just my opinion though...but if you really want to build one from scratch, i would go to MWAVE...