I was browsing Harbor Freight yesterday and found a dandy little 800 watt generator (item 66619) for $109.99. It puts out only 120 VAC, no 12VDC. It is very compact, weighs 40#. I was going to buy a deep cycle battery. They cost $67 in my area and a good charger for it is another $50, so this little generator seems a good deal to me. I'm using a 5S2P 2300 mAH A123 battery in my RC Focke Wulf and don't want to charge it from my car battery.
I already have a good 120VAC-12 VDC power supply (an IBM hot swappable server PS 12VDC @ 37 amps) I use to power my FMA Cellpro charger so I can just plug it into the generator.