Greetings Anwar.
Thanks for clarifying.
Of course there is nothing wrong with buying/selling merchandise. But preaching? It should be free of charge regardless of spending a little time/money on paper...etc. Let it be as charity?
GOD has been giving as long as humans existed,but never charged a single penny for anyone. His scriptures have come free of charge. Let us keep it that way.Or at least give a choice -donation from whoever can afford it-.
Again that is only my opinion.
GOD bless you.
Peace.