Good luck guys! You seem to have all the right ideas. A robot with good drive can win battles, there is no shame in going the rammer-route for a first robot!

May I ask how many motors you intend to use? With 4 motors on the Gimson scale you will need a more powerful battery than a single NiMH pack (they can only discharge around 30 amps). By need I mean you may want, or you'll feel a loss in power. A pack like that is perfectly good for a 2-drive-motor machine.

For ESCs I'd recommend the Botbitz ESCheap85s, they're very good for the money. You will need two, though, one for each side.

For plastics in the UK, I believe most of us use http://www.directplastics.co.uk - lots of choice and a reliable service.

Hope this helps! I await piccies.

Edit: Just read you intend to use ball transfer units, suggesting 2 motors. Never mind! You could use the ESCheap25s by Botbitz to save some dosh, they should handle a single Gimson comfortably.