I saw a neat deal at the field last weekend. One guy had a double-decker Walmart tool box, with wheels and a handle no less. He had "aerated" part of the lower box to house his battery and installed a power panel. It was pretty slick and probably cheaper than the fancy made-to-purpose units.
Mine is a converted tackle box. I carry a fuel can with a bulb pump, and use a glow starter with a built-in battery and a chicken stick instead of an electric starter. The only down-side I see right now is that I have no way to field-charge batteries. The extra trips (very short) back and forth from the flight line to the Jeep are theraputic.
I liked the "under the radar" line. Very descriptive of stealth modeling.