so your looking for a wedge shaped flipper. you will need :

20 drive : i suggest 2 Argos 10 quid cordless drills
15 blue wheels: ask in the wanted section or ask grant ( ask someone for his email )
40 speed controller : 2 x mtronics eco 27 speed controllers
35 a radio system: i recommend the planet 5 2.4 ghz system
10 MDF for the base , get it from B&Q , 2-4 foot sheet will do

so total for a moving base is about 130 quid ( no pound sign on my keyboard :P)