Fontana sold out last year (as of now there are almost 38 people already signed up for Vegas, 35 for Pikes Peak, 18 for Fontana). The sooner the better I would say. I believe they limit the amount of entries to 80 or so per event. You have to put a deposit of $200 for each event. Not sure if that is fully refundable or not, but it can be transferred to somebody else (i.e. event is sold out and you can't go, you can sell your spot to somebody else)

I was going to do Vegas, but would rather do the CPW speed festival instead.