If I can afford the warm socks, I like to race with AMEC. The warm socks cost almost as much as a day's entry fee (about $40). A tank of regular unleaded should also be included in the budget, because there's lots of track time (usually at least 1.5 hrs). The Menard studded tires can last virtually forever on a low-HP car, or the unstudded street-legal class is a blast too.