Add techbargains.com and Fry's to the list. You definatley get what you pay for with a power supply. If you take time and search around there should be a deal on antec 420's out there. Still not cheap, but a 20 dollar power supply is risky. You will be upgrading or re-building in the future, and the future includes 500+ watt power supplies. This is something you can interchange in the future. Might as well invest in a good one.
Forton also makes a good PSU and good prices. Antec is so-so at the moment. They use to be top notch but lately have had some major quality control issues. PC Power and Cooling is top notch but has a price tag to reflect it.