determine how many people will be on staff for the job. how much you pay an hour times the amount of staff, times the hours it would take. add the cost of the materials and some of the cost of the equipment you use. now either double the price or go 3/4 more. if all the above costs you, say, 700$ for one nite, charge 1200-1400$. to get into a service business like this you either have to have the best people or the best price. it seems your just starting so, you might be better off setting your priceing lower than normal to get some business, then increasing the price after the customer is satisfied with your work. also, to clean a bank, your business must be bonded or o.k.'ed by the police, most offices too. your question has many variables that can come into play, but this should start the process, good luck in your entreaupernerial skills