Call up various rotary shops. The eccentric shaft definitely wouldn’t be the hardest part IMO. So many capable rotary guys in North America. It’s just the $$$$ like you said lol. Rotary anything is expensive because it’s such a specialized market. If more companys invested in the wankel waaay back in the day before Mazda bought up the rights (I believe it was that) then things would probably be better. Competition keeps shit in check, and Mazda doesn’t have any other competition as far as rotary design goes so it’s take it or leave it unfortunately.