The way I read it, the basic fee of $45 will allow you to enter all the events you want, CL, FF, RC, and/or Scale. If you miss the June 25th deadline, there's a $50 late fee, for a total of $95. Having paid this, you're into The Nats, but no events.
CLPA events 325 or 322 (not both) cost $45.
All regular CL events cost $10 each.
First Scale event $20, additional scale events $25 ( a unique quantity penalty).
So your total fee (assuming you're not late) is $45 plus the fees for the events you enter.
So one Stunt event will cost you $90.
PS:
There's no penalty for adding events on site. You could just pay the $45 plus one $10 event, (total of $55) and add the events you decide to fly when you get there.
PPS: If you just fly non-Rule Book events, like Speed Limit Combat, the AMA fee is $10 (for all you can eat), plus whatever the SIG (MACA) charges, $10 in this case, total traiff, only $20 to compete in The Nats.