I have only recently started doing club track events, so here's a novice's point of view.
You will find pricing to be best through the local car clubs. The BMW and Alfa clubs are your best bets. The Alfa club usually only has 2-3 Alfas in attendance, while there are a bunch of Bimmers, 'Vettes, Porches, Miatas, etc. Events are usually held during the week for purposes of track availability and keeping prices down. You'll pre-pay, and events are typically held rain or shine. Driving in the rain, as I did for my first driving school, can be a surprisingly good experience for the novice. You will be forced to focus on being smooth and finding your line rather than going as fast as you can.
As Ensi mentioned, a car control clinic (CCC) is a pre-req for lapping days / high performance driving schools (HPDS). Try to get your CCC done early in the year to give yourself more flexibility on the other events. A CCC with one club should satisfy any club's requirement.
Safety is always of paramount importance. Helmets are required and usually available for rent for a nominal fee. The BMW club does not permit convertibles (even hardtops) though the Alfa club does. Roll cages are not required. You must provide proof that a safety inspection has been performed by a local, certified mechanic within the 30 days (60?) preceding the HPDS or lapping day. It's not required for the CCC.
Lapping and HPDS days are generally set up with 4 driver classes (A-D) based on experience. Each group usually has the track for about 20 minutes at a time, so you'll have some downtime to get something to drink, let your engine and brakes cool, and check tire pressures. You will have an instructor with you for classes C-D, and must be signed off to drive solo in class A-B. You'll see a lot of the same instructors at the various club events.
Check out the club sites:
http://www.bmwpugetsound.com/
http://bmwpugetsound.com/drivingevents.htm
http://www.nwalfaclub.com/track/calendar.php