How to do it Cheap, but Right

Honestly, building a computer is pretty simple as long as you check for any requirements listed for the individual components. An easy mistake is to buy a graphics card that requires a 500W power supply when you have a 400W, or even noting that, but buying a motherboard that only handles up to 400W. So the biggest downfall is not checking the requirements.

Try to find a few online sites that list discounted parts. There are a few big names out there, and bookmark them all. Then check the price/manufacturer across them. Try to stick to name brands if you're unsure of off brands, and to make sure you're not getting someone's untested house brand, cross reference them. If a certain brand is listed on most or all of the sites, you're probably fine.