The 5 day school is the cheapest rally seat time you can buy. In 5 days you'll get ~30 hours of in-car instruction, and near ~150 miles, of closed stage roads. Including car use, fuel, spares, instruction, safety gear, and all the cones, trees, rocks you can hit. Day 5 is designed for more stage rally simulation; pace notes, time control, vehicle recovery, building a team, and so forth.
I rolled there once and the first word out of my instructors mouth were into the radio for someone to bring up another car so I can keep running. Good luck getting that sort of service at A Skip Barber school.
Also, as noted above, if you think TON is costly, you exploring the wrong sport. Try a 1-day "rally" experince course first, for 600 bux its dirt cheap [yes, pun intended]