I'm on a 500 watt 21 amp PSU, with an eVGA 8800GTS. You should be fine. You can buy a high range PSU for a lot less than 150, see link below aprox 81 USD at 700watts: http://www.buyxg.com/store/item.asp?key=PS-109-110 That will more than cover your minimum, it's 40A on the 12V rail.
I just bought a geforce 8800GTS and the requirements say that it needs a 400 watt power supply with a minimum of 26 amps on the +12 volt rail. Now, since they dont really even make PSU's (as far as I know) that have a single 12V plug with 26 amps, I assume they mean the amount of amps across all of the 12V plugs. I have…