Another option might be one of these puppies (the first 3 items shown)..
http://search2.hobby-lobby.com/psear...hp?uid=2&q=bec
BEC= "Battery Eliminator Circuit", used in model aircraft to drop flight battery voltage down to 5V or 6V selectable, nice smooth regulated DC for powering avionics. These are switchmode, which means they don't heat up like the older 'linear' BECs which were resistive droppers.