Instead of buying a power supply, if you have any soldering skills, check out some of the PC power supply conversions that have been done. I asked a coworker for one (he is an egghead), and he gave me a 250W power supply. I just took the cable and found out what connections to short, and which ones to make into + and - leads and within about an hour, I had a supply that will give me nearly 20A of 12v DC power for my charger(s).
Curtis