some motors I found

[Mega Masher]

Hi people, I found these motors on hobbyking, and they look just like the ebay motors only run off half the voltage and have a lower speed.
http://www.hobbyking.com/hobbyking/s...1_Gearbox.html
Hope this helps someone

[Niels - Team K.a.L.M.]

You can find 300rpm (and lower) gearmotors on ebay that still run on 12v. Thereby offering more power for the same weight.
The pricetag is also roughly the same depending on what seller you find on ebay.

If people are truly limited to two cells it might make a decent motor but the difference in power to weight is huge.