It's tricky...
I have bought a number of second-hand 12th cars over the years and each one has been built poorly and required a rebuild. People usually give up 12th because the car doesn't handle because it is not built and prepped properly.
For me, a 12th racer since 1976, that's no biggie. For a new racer it can be very dispiriting when the car you get handles like a dog and you can't find a way to fix it.
I have had a long affection for Associated cars; they have always given me my best results. Nonetheless, the current Xray cars are really (really!) good - easy to build, give a right-first-time result with good handling and have a good tuning manual in the kit.
Much as I would say that Associated, Yokomo, Zen and many other makes are good cars, for a new racer in 12th the Xray will give a better result due to the quality of the parts and the information in the tuning manual. There are set-ups to be had from a number of drivers on 'tinterweb and the parts are easy to come by.
If you do find a car second hand, then try and find someone at a 12th club or a BRCA National to put the rule over it and check it is properly built. Let me know where you are and I'll recommend somewhere to go.
Once you've built it up and had it checked it will give you years of good service. Most 12th drivers keep the same car for three or four seasons. Very little changes and spares are confined to a few items. Front springs should be replaced every three or four meetings (£4!) and the shocks and diffs need a clean every meeting. Apart from that they go on... and on and on and on!
Good luck; come back here and ask anything else you want to know. HTH
