What is the WT actually printing these days? Think about all the bound books we used to have and more constantly coming out. They were ramping up printing of this and that all over the place. Growth growth! We need more bound books!
Now what? Two little skinny slivers of a magazine and an occasional tract? Not to forget the much ballyhooed silver Bible. They got as much wind out of that as they could.
From your list, I will go with Regional Conventions in Soicety owned venues ($). And official but unofficial tithes, promoted as Biblical since the Israelites were asked to bring it all in for the temple building, and thus they did. You know the GB and Bethel heavies cannot stand it that they see wealthy brothers.