Stalker + GPRS Shield power?

Stalker looks like a great base for a project, but how would I reliably power the Seeduino Stalker and the GPRS Shield? Looks like the stalker takes 3.3 or 5v DC in, but I have to assume with a max transmit at 2w, the GPRS Shield requires more than that?

Does the GPRS Shield mandate use of the additional power supply (jack shown), and if so I think this is 5v DC, but how many amps will it draw?

Thanks,
AJ

Different working condition have different needs power , I think it better to used Simulation power to meansure it by yourself.