I don't entirely agree with the notion that you need a couple hundred quid for a feather. I don't understand where that cost comes from. I suppose it goes up if you're not willing to do some work, but if you're up to making the wheels and such I can see you building a fairly competitive robot for not all that much.

2 drills: £20
2 BB 25a ESCs: £30
Radio: £30 new for not even the cheapest option, maybe less if second hand.
Battery: ~£15
Chassis/amour: £20 or less if you have access to scrap materials
A further £20 for bits and bobs.

£135 for not the dead-cheapest route. Depending on the availability of parts or you may even have some stuff already, perhaps even less.

Good luck mate. :)