How to build a $20 47A power supply

[brainanator]

does the PSU need that much cooling? You probably aren't taxing it very much at all. Maybe if you want to future proof it for expansion.
Also, depending on how smart the PSU is, it might monitor fan speed and no operate if it senses a failed fan.
http://dx.com/p/mini-1-5-lcd-digital...-x-lr44-126092
That's a little temp display I got from there one time. Only displays in C.
Mines been going for 3 years on the same batteries. Not super thin or high tech, but it's cheap.