I did find a little in a prior proposed trial event. Supercapacitors are available from Digikey and Mouser, generally 5F capacitors have a max voltage of 2.7V if the restriction is 3V max label. I have not found any that are labelled 3.0V. Unfortunately, this means simple charging from dry cells may not be possible, as exceeding this voltage for more than a second is not allowed (per the spec sheet). The rules say the capacitor may not be charged with more than 3.0V. Not sure if this means the input to the charger (if we used a digital charger like those used for LiPo's), or the max charge into the capacitor. I guess it would be easier/safer if they allowed a 5.0V label on the cap, but limited the voltage at launch to 3.0V. Then charging could be as simple (I think) as connecting to two series dry cells.
Motors, with and without gearboxes, are available at Plantraco: http://www.microflight.com/Online-Catalog/Motors/GB05-Gearbox-with-motor
Should be interesting to try things out and see what works!