The price of the bike, then you've got your engine tune which will be between £500 and £1000. If you have a highly tuned engine you'll have to have it refreshed every other meet (another £500) a competitive engine will need refreshing once a year.

Then...............

Suspension rebuilt
Race looms
Race ECU

Race Entries - about £170 per weekend
Fuel for the bike
Fuel to get up there
Tyres
Brake pads
Oil
Van
Caravan - a must!!!!
Paddock Stands
Tyre Warmers x 2
Awning
Tools
Spare Lid, Leathers etc
Generator
Spares
Fairings
Tyres - £200 a set
Wet Tyres - £200 a set
Spare wheels

Spare fooking everything
and that's not taking into consideration if ya crash or blow up an engine but most of the above you can sell after the year has finished and recoup some of the costs

If you wanna go do it, then go do it!!!!!!! Seriously, if you thought track day's were a hoot wait till you have a go at this....