It depends… on how good new equipment you want, and what engine.
Myself - I went cheap since it was my first year in karting and I just wanted to get a feel for it and have fun doing it without killing the bank. Here are most of my costs though the year. Note that the place I race is a 1.5 hour drive each way, and the mode of transport is an old small block C1500 pickup, so fuel ads up.
Kart - '08 GP Racing frame with 80cc Honda shifter engine with fresh top end - $1750
2 spare coils (after 1 failure) - $67
Spare clutch kit - $39
2 sets of metric front hubs - $110
4 alternate rear split hub gears - $110
1 new set of tires - $200
4 sets of takeoff tires (1 race with team from ebay) - $200
1 new set of wheels + 2 new wheels to convert from CRG to metric $230
AMB TranX 160 Transponder - modified to take 9V batteries - $125
Mychron 5 - $485
Fly360 4K camera - $200
Kart suit - $200
Helmet - $95
Misc nuts, nylon ties, etc - $20
Yearly club dues - includes unlimited practice time - $200
Race entry fees - $40 x 9 = $360
Race helper pit fees - $8 x 4 = $32
Gas (races plus a few practices, avg) - 13 gal x $2.40 x 13 = $405
Highway tolls - $2.55 each way x 2 x 13 = $66.30
That should be about it. So all-in about $4900. Certainly not cheap, but not horrible. The 1-1/2 hour drive each way with tolls does not help any.