This may not be applicable to you situation, but I have had good sucess with the following method:

Find one of those little shops in a convient location that builds machines. There is 1 near my apt. that has a top end gaming rig (no monitor) for about 1000 (maybe short on ram...).

Basically, these is maybe 20-25% more than putting it together for yourself, and maybe 10% more than buying on line BUT if it's some how bolluxed or breaks, you can get it fixed WITHOUT shipping it anywhere.