Congratulations on choosing your car. That is half the battle. It does make sense to buy a car that you can get assistance with at the track.
The easy way out is to buy the RTR but If you buy the kit, you will also have to buy a radio, servos, engine, pipe and a bump box. To answer your question, GO Tech makes an awesome affordable engine and they have great customer service. There is a tread on this forum for those engines. Check it out. They have a race spec and a sport 3 port, a 5 and 7 port. All of them are great engines and range from the $115 - $210.