I used a RV 50amp 240V breaker box from Progressive Dynamics that I bought from Randy at Bestconverter.com http://www.progressivedyn.prawnserve...?CategoryID=34
You probably want a 30amp/120V box. Those are available from the same place, but only as a combination box with 12V-dc fuse slots.
You can also buy a regular circuit breaker box at home depot, but I didn't find any that were the perfect size and capacity. If you do a 30a system you can only have five separate circuits, plus a main breaker, for a total of six spaces. You also need to separate the neutral and ground bars.