A flat fee per file seems to make the most sense, since their operation costs are per transaction. They should just figure out how much it costs them per transa

A flat fee per file seems to make the most sense, since their operation costs are per transaction. They should just figure out how much it costs them per transaction, then bake in a percent of their startup costs to reach the black in a reasonable time and use that as a flat fee. I can't see a justification for a percentage approach, its the same amount of work either way on their end.