Hey Nugg,
If you fancy popping down, we got a race meeting this Sunday if you want to come and have a look? I can more than happily show you over my car you wish and advise you a bit further.
The B4 is still a good car but most of the 2WD cars are mid motored not rear now which I would most people would recommend to you. The Durango is a very good car and they do pop up second hand, I got mine for £120 over a year ago! Other cars I would recommend is the Yokomo B-MAX 2 Mid looks to be going pretty well and the Schumacher Cougar SV2 won our last meeting too so that clearly has the pace.
2WD is the way to go though, it's our most popular class and it will teach you set-up and to drive well. 4WD and Short course we don't get quite so big a turn out but I am sure that will grow in the summer
£130 Car
£50 Hobbywing Xerun 120a ESC on ebay
£30 7.5/8.5 Motor
£30 Ansmann/Flysky 2.4ghz Transmitter and Receiver
There's also a range of skills as the club so your lad will fit in fine, I started when I was 5 and just ran in and crashed with everyone else