The power supplies that Radio Shack sells usually don't have sufficient amperage to run the larger PSRs. The spec's for the 2000 will tell you what kind of volts/amps to use and the polarity will be marked on the input. You probably can find a cheaper unit as a portable refrigerator power supply (the kind you plug in your car cigarette lighter -- this "power supply" lets you use one of those with AC in the house). Target sells these for ~$15. But if you don't understand volts/amps/polarity you'd better get one from Yamaha, otherwise you could ruin your synth.