Actually, that is an article you will likely sell many times. Granted, you may never sell that particular amount to that customer again, but if you define the "product" as one hour at $xx.00, you can bill for the appropriate quantity of hours. Alternatively, if the time is not strictly on a standard per-hour basis, just make it $1.00 worth of billable time and bill for the appropriate quantity of dollars. You can set in admin to allow fractional quantities, and two decimal places.