but expect it to be VERY ugly..

Case - $9.95
Motherboard - $52.99
Processor - $60.77
2x 256 RAM - $38.00
20 Gigabyte HD - $25.95
DVD Drive - $12.00

osx86project.org - has the full story http://osx86project.org/index.php?option=com_content&task=view&id=27&Itemid=2

you can also try and install it on your current PC.

http://osxonpc.com/