I agree with Daff , dont sell yourself short ,I dont know how far you will have to travel or if you can even use his water,I know from expirience, I used to wash about 60 utility trucks for the power company and I was washing them monthy I charged them 35.00 a truck it only took me 10 min to wash one truck ,I I was getting a good deal!! I think a school bus is worth every bit of 35.00 or even more !! I also have been doing pressure washing part time for 5 yrs . Good luck!!! P.S. I used a truck cleaner from car quest called TP 625