I just realised that comes across very snarky.
Building your own is really your best bet with a desktop computer. You get so much more for your money. I just bought two new fans for $25, both fancy blue LED fans. Fans are cheap, probably going to be your cheapest parts. Baby is much happier now that she has working air cooling again. Cooling is very important. Unfortunately as I said above even if you build your own, a bare-bones gaming PC is still around the $1000 mark.
Whatever you get, whether you go new or secondhand, Gigabyte motherboards are wonderful. They're what nearly every pro gamer uses and they LAST. I'll be getting the second best on the market. I'd go for the best but it just doesn't have enough USB ports for me! Intel processors are great, and nvidia graphics cards are the best. If you can get it Corsair brand, do so. I'll have Corsair power supply, RAM and RAM cooling. They unfortunately don't make any blue LED fans and all my fans are going to be blue LED because I like glowy things.
Gigabyte, Intel, nvidia (especially their offshoot, EVGA) and Corsair where you can! BitFenix make good fans, as do Thermaltake. Expect to spend a little more, but if you get good brands, you get a quality computer that lasts, and you'll spend a lot less in repairs in the long run. Baby has been used and abused for eight years and she's still going!