I bought a 240v to 13.8v 8A regulated power supply from jaycar for $40 that I use at home, out and about I power the mount from a 12v 17Ah jump starter kit...
Both use cigarette style sockets to supply power, and so no crazy adapters were needed..
Both work fine, the jump starter lasts about 7hrs (which is plenty) however it requires about 20hrs charge time so using it on consecutive nights may be difficult..
If you will be using your scope mostly from home or places with power, then by all means, go for the regulated supply (its cheaper than the battery) and that way, you can eventually run your dew heaters off it to...
Alex.