You may be better off purchasing someone's older system they want to get rid of. I'm sure someone on the forums here has a $400 setup they are wanting to sell. My issue with barebones systems like those is that they usually consist of low-end parts, which go bad and need replacing. This is the same reason those of us who still remember Packard Hell, remember it not too fondly.
Try posting your price limit, and what you are looking for on the "For Sale/Trade" forum, you may be surprised with what you can find. In my experience, all the members on this board have been honest and helpful.
If that doesn't appeal to you, try looking around for a barebones system that comes with some name brand equipment, especially for the motherboard.
Hope that helps!