Hi Glen,

To see how cheaply it can be done I built a simple robot last spring out of 2 9.6 volt drills (Argos, christmas special, £10 each) and used the drill batteries and rechargers. Total cost was about £75, not including radio gear. Armour was 28 mm wood, held in place by 6 mm roofing bolts. I did fights with spinners at the Cambridge event (including Dragonstrike and Vortex) and at the end of the 2 day event it was still working. Hardwood makes great armour.
It is possible to make a robot that can stand up to competition for relatively modest amounts of money.