+ fuel
+ accomadation , before the event starts and after
+ transporting yourself/ bike to scrutinerring, accomadation while there
+ buying the bike, building it.
+ buying the irirtrack/sentinal recivers, all the gps wiring.
+ insurance etc
+ if you want proffesional pictures you have to pay a company to take them of you!
+ if you break anything while there and want to buy an engine or a wheel, out comes the checkbook.
The list is endless, even if you do it unsurported you will still have to pay ASO to transport your stuff between each bivoac.
I have a friend who did it last year, Mike Sheperd (Kiwi) living in Uk and he estimated that all in it cost him £45000 ($73000) and he could only estimate it as ASO kept adding bits to the final price and he lost track of everything he had bought.