Analogue-sequencer

Well, I'm sure this is a ridiculously basic question, but I'm quite 
ignorant about stuff like this..

I have a ready made p3 arriving soon, and I need to pick up a U.S. 
power supply for it, described by Colin as 9v DC @ 500mA, on a 2.5mm 
barrel connector.

Is this a common enough item that I should be able to pick one up at 
a Radio Shack, or will I have to do a little more digging?

Thanks,
Gene