Gimsons all the way
with a 100mm actuator also a gimson

also there wheels a SMIDSY esk, make it small and make it in metal, O and get the dude who owns SMIDSY to measure it so you get the proportions right

http://www.gimsonrobotics.co.uk/GR01_pl ... motor.html bargain at £25.90 each

http://www.gimsonrobotics.co.uk/GR01_pl ... motor.html you wont look back