Thats a tough one Wyatt. If there are no friends/squad mate variables to consider (which usually lowers the cost), I'd recomend doing some soul searching to put a price tag on a lump sum fee of what 4+ weeks of your time will cost. I would be surprised is someone actually ofered to pay hourly.
OR
Have this person pay for the supplies to make 300 sets of Gaskets in return to build a TFA kit. I don't know how much thats worth, but just throwing it out there.