Nightjar, I would probably look to go down the used car route to pick up a slightly newer model. I remember my time from racing an old car against guys with the latest tech and it was a struggle. Admittingly, my car was old and pants though whereas at least your car is/was a good car in its prime so you will probably do better than I did.....
The new kit option is out of reach as a schoolboy I would think as unless you are especially good at sweet talking money out of your parents / guardians then its likely to just be too expensive. Ive spent over £900 so far and Im not finished yet!
You can pick up a bargain if you look in the right places for a used car though. If you were looking for Nitro then I would point you in the direction of Tooleys RC in Northampton. Last Saturday I took my old Xray XB8 in there and sold it to the shop for £200. That was absolutely 100% ready to race though, I mean literally everything you needed was already installed on the car. Because I wanted to get back into racing 1/10th Electric then I just sold the whole lot in one big ready to run package. I bought the XB8 to race but just didnt get round to it and when Tooleys got rid of their track it just killed it off for me as whilst I dont mind travelling to race for big meetings (if Im good enough) I wanted a 'local' to cut my teeth on and couldnt find a suitable, regular meeting to attend.
Getting back to the point though
as well as my old XB8 (which admitting is also a little dated now) they also had a Losi 8 rolling chassis in the shop with thousands of spares included which was going for about £150 I think and he said it had been there a few months so you could probably have shaved a bit more off that price....