That's a great sport! I ran Jr's after we got out of Motocross. Made the jump into a full supercomp rail car very easy. well as easy as it can going from a 8.x @80mph 1/8mile jr into a 5.0x at 135mph 1/8 rail... lol Jr's can be quite expensive as well, but the nice thing is that it's all dial in racing(mostly). so if you can't afford the big bore high dollar engines, then you just run slower times. It's all driver. And relatively safe.
I'm a bike guy though, so it was back to roadracing and motocross after high school.