inverters

Due to the high power output of these devices, they're generally not powered by D-cells, 9-volt batteries, etc. If they have internal batteries at all, the batteries are rechargeable lead-acid gel cells or equivalent. This one by Duracell, for example.

Alternatively, you could use a 12-volt power pack (using C- or D-cells) and connect it to an inverter having a 12-volt, cigarette-lighter input. 12-volt battery clips are available at Radio Shack (assuming you live in the US). Clip the cigarette-lighter plug and wire the clip to the inverter through a switch (unless the inverter has its own built-in switch).

Good call. Wal-Mart's Duracell equivalent sells for much more. This Xantrex unit is almost identical but half the price of Wally-World's unit. (Sparky, does Wal-Mart have a presence in NZ?)

This inverter also sports a 'modified sine-wave output (MSWO).' You want this! Cheapo inverters often have a square-wave output that makes life hell on transformers, motors, and other devices (usually inductive) which can overheat because of the high harmonic content. A pure sine-wave output is ideal, but such is usually found only the big-ticket inverters. I don't know if Duracell's unit has a MSWO or not. (MSWO generally means the output is a piecewise approximation to a true sine wave, but looks as though it were constructed from straight-line segments. Still quite a bit of THD, but not nearly so bad as square-waves [technically also AC, but nothing like what one is accustomed to from a wall outlet]).