i can tell u have i have alot invested in the small amount of machines i make and dont make much profit if any i do it cuz i like doin it but i too had to learn to make my parts myself but factor in the cost of these machines to make them and labor then u have to build them and hope for people to buy them now i havent built a rotary yet but i will tell u all tthe places i seen they have minimum orders for good motors like 1000 min or 5000 minimum so sure if u want to buy 5000 motors go ahead ull never have to worry about a replacement and ill buy them from u 2 at a time for the next 5 years now u see y they sell them for more