I would start with fewer. You don't need a big expensive cage like you do for fruit trees. You can use cheaper stuff, plant, cage, let grow a couple years, then buy a few more, or propagate from cuttings. You can then move the cages to the new shrubs/cuttings when planting them out.
The established ones you can lean over and burry. This will make the shrubs sprout more and grow wider. It will take more time this way, but it will cost a fraction of planting and caging 100 in one season. It also spreads the work out over a few years, which is great.
I've been meaning to make a video about this process, but the weather has been brutal. Vicious wind and rain all week, blew my gas grill off the deck and threw it 6 or 8 feet onto the path today. When the weather clears, I'll make a brief video about propagating and expanding red and yellow dogwoods.