An AC to DC power converter from radioshack with a 100 watt rating or better will serve you well. Fan wires may need to be cut and wired onto the leads of whatever PSU you buy. PC fans come in all shapes and sizes. Get the one which fits best for your grow area. They also come in different RPMs... Higher RPM fans 1800 rpm and above can be aubible from a short distance. higher RPM fans like 3000 rpm fans can be heard from across the room and are quite loud. In my grow box I am using 1800 rpm, 120mm PC fans. I would go with a 120mm fan if you can. They push more air and do it at less RPM than a smaller fan. look on ebay for DC power supply, also look for PC fans by searching 80mm, 90mm, 120mm pc fan