That professionals (i.e. Dan and Dave, De'vo, Daniel Madison etc.) buy each others material? Like do you think Dan and Dave have a copy of Cradle to the Grave or Jerry Cestkowski has a copy of Lethal?
I do remember hearing Jerry mention that he has some of the Bucks material, however I wouldn't expect the same from them. And, I don't think they particularly buy each others material, I think Jerry was saying they (Bucks) sent him material, but don't quote me, that just what my aging fragile rotting brain remembers.
i too think that MANY celebrated professionals get a lot of material to review and recommend. this is the process of PEER REVIEW. sending a complimentary copy of books/materials is a common thing.
but i do feel that a lot of the performers buy stuff to support the creator.