i think if you want to go budget (i do everytime) the best thing to do is open an old pc. if you can find a way to hav the power supply turned on (some need connecting an "on" lead to an earth) then all u need to do is use the yellow (usually) for 12v dc. otherwise you could try a car battery charger, depending on what amps they are rated for. i think ours is only rated for 6, but its a lame crappy one