^Karting is good, cheap fun.
A typical track weekend for HPDE excluding entry fees costs approx $500 excluding entry fees for me, instructing.
$150 in gas
$200 in tires (1/5th of a set of street tires)
$100 in hotel for one night
$50 in meals
Racing cars is even worse... Spec Miata was $2500-3500 per weekend including entry fees, race gas, 2/32 shaved tires, mechanic support, engine rebuilds, etc. and that's just a Miata. Running less aggressively shaved tires, stock motor, regular pump gas, and doing the work myself would probably cut that in half.