It all started by some JW's setting up tables in flea markets and even trade shows. They had some initial success from the stories that I heard. The COs then started encouraging other congregations to do the same. Finally the branch got involved and decided to regulate everything.
I won't say how I know because it may out me, but the WTB$ sources all this stuff, the carts, chairs for halls, etc., from China. They have warehouses there and everything. Of course it's all hush-hush and run under different corporations.