Yes, racing is not cheap, especially if you crash or have to travel. Plan on spending more than you plan on spending.
The bare minimums for me at Blackhawk (im on tight budget compared to many others)
Gate Fee: $25 / person for saturday and sunday or $15 for sunday
Races are 80+50+50+... only if you pre-enter 2 weeks ahead of time. The 1 or 2 ten minute morning warmups/practices are free if you are registered to race. The racer practice/trackday that they usually do before a race weekend is ~$125 if you preenter.
Transponder: $80 to buy your own
Race School: $200 - if you pass, your license is free that year.
Race License: ~$125 / year each year after
Fuel, food, etc: $100 min. / weekend
Lodging: free to camp
Bike maint: Brakes, oil, chains, fork and shock refresh, etc - $500/yr if you dont crash
Tires: $365 / set. I can get away with running one front and 2 rears a year if I do the morning practices and 3 races each weekend. So I plan to spend $560 on race tires this year which will only be used at the races and I will swap rubber for trackdays. As an amateur, I ran street tires and used the same set all year for practices , races, and trackdays - so about $300 for a year. Keep in mind, I'm a backmarker, so I dont use tires like some others do.
Dont forget about spares: Levers, clipons, pegs, etc are bare minimums IMO.
Other things: Tire warmers, Ez-up, tools, stands, spare wheels, etc...
The list goes on and on...