Build one, don't buy one!
I built a Hackintosh around a year ago now, after flirting with the idea for about a year before that. The machine I built cost me around £400 (but I did salvage a case and some drives) and it, at the time, beat all MacPros hands down. It's still an awesome machine, and runs everything I can throw at it, including Photoshop, Final Cut, etc without a hitch. The challenge of building it was part of the satisfaction, and I would recommend anyone who wants to use a Hackintosh to go this route.