The only way for a shop to be efficient at building crate engines is to use all new parts but that option doesn't exist for SB or BB Mopar engines. So the whole concept of crate engines for SB or BB Mopar engines is lacking. The shop I work with has a supply of core engines and he builds one BB Mopar per month on average. That isn't exactly a crate engine shop but he builds them often enough that he keeps parts in stock and he knows how they go together. If you go to a shop like Barton or Best Machine they might build more than an engine a week. Volume helps to keep the price down but nobody offers true volume pricing on Mopar engines since nobody is building enough engines to drive the price of parts down.