This topic is interesting, and I have wondered the same.
Jesus said "freely you have recieved, give freely".
I lean towards the opinion of
@Armchair Apologist . At the same time I am concerned about the kingdom work becoming a business.
I think about the money changes in the Temple.
I liked how John MacArthur made so many if his works avaliable without cost online. One could provide their own resources and print them. Or one could purchase them as a book.
But in the end of the day we are to equip ourselves as congregations. God gifts His churches with a pastor, with various ministers, with teachers. I am not sure that this should be outsourced.