I wouldnt get the JLR .12, they just won't last. I had 2 JLRs, both blew rods very early and the P/S never lasted more than 6 months. 2 engines, can't be a coincidence, though the rod metal was very poor. I would either get an RB Junior, Nova N12, or a GRP bundle if you don't race with the pros. Think of this:
Cheap engine = not cheap in the long run + not that powerful.
Good engine = 300-400 at least + pipeset.
Kick-ass engine = good driving and setup!
+ knowledge of tuning and chassis adjustments.
You can come first with an RTR engine as long as your car is setup correctly and you are consistant.
If you spend too much money on engines and still don't win, you will always be last.