Ok so if you've read my profile here, one of my goals is to create/produce a low cost, versatile micro/mini robot that could be used as a swarm bot.
Currently I'm trying to source some decent tiny gearhead motors for under $12 dollars. Today I've come across these:
Also there are some 3V gearmotors of the same dimensions with varying RPMs (from 30 to 100rpm) available as well. The torque ratios are not given for those, however.