It depends. If you can find a group that is renting the track then it is up to that group for the cost. When I was going on a regular bassis I would pay ~125 - 150 for a day. That was typically 4-5 20 minute sessions. That is way more than enough to wear you out.
If you go to High Speed touring they have an annual membership fee + the High Speed Touring fee. Unless you plan on going more than 2 or 3 times in a year, find a group that is going.
The Z Club of Texas is there every year. The Porsche club is there twice a year (although they restrict to marque cars). There are a number of people that sponsor events each year and you have to watch forums.
http://www.greencountrymotorsports.com is a good one for the Tulsa / OKC / Ark area. There is also the
http://www.oksc.org for Subarus that occasionally have events.
You may also watch for events at the Sherrifs track in OKC. They are fast an open with a simular effect as Hallet but only one lap at a time.
The track does not perform an inspection on your car and expects you to have performed the correct maintenance and have a reliable car. They have a check sheet of things you "should" do before going.
What I would do before trying to run your car at Hallet is.... 1. Replace the Brakes and Brake Fluid. Hawk HPS Pads, Porterfield R4S or other simular pad. Nothing you pick up at a local Auto Parts store will stand up to that track. Replace your Brake Fuild with ATE Super Blue or Gold fluid. Make sure you have good rotors. 2. Replace your tires. Find a good set of used Toyo RA1 tires. a 205/50/15 would be a good start. You 60 series Michelins will roll over, squeal and possibly chunk. They would probably be done after if you ran hard during all 5 sessions. 3. Invest in a good 3" lap belt. A full 4 point is great, but if you don't have a roll bar don't do it. 4. Make sure you have an up to date helmet. It does not have to be SA. An M rated helmet is ok. 5. Be sure to bring pants / jeans and a long sleeve cotton shirt. You do not want to wear polyester anything if your car is on fire and you are still in it.
Expect your first time out in that car to run high 1:40's to 1:50's. My fastest time in my RX-7 is a 1:34.00. My fastest time in my friends RX-7 was a 1:32.00. (With better tires and a Wing he was able to run high 1:28's in his car.)
If you want to see some laps of the track I have a number of in car video on my website.
http://www.4113pittsburg.com/garage Scroll towards the bottom. Hope you can make it out there because it is a blast.
