Go have a look at
Nitrotek. These are really just for a bit of fun and not your serious racers, but a very good intro into the world of r/c, both electric and nitro. If you're looking for something a little more serious, I would recommend
Benracing - that's who I've just pre-ordered my HPI Hellfire through. Ben Kelsall is a great guy who will give you all the help and advice you could ever need.