Cheap? Primary gaming pc/laptops are typically more expensive. So if you really want to play games and on a good system, you're going to have to pay the extra money.
I dunno, I've seen some pretty spiffy gaming systems on eBay for under $1000. Heck, if you're willing (and have the know-how) you could buy the motherboard, CPU, RAM and video card for around $500 (Provided you already have a PSU, case and harddisk).