I am not involved so I can speak without any ulterior motive. We had a co-op about 5 years ago which went very well. It is possible to work a deal with a nursery but it requires one person to be in charge to handle the order and payment, payments in advance of course. The nursery most likely will deal only with one person, both for payment and shipping address. That one person must break down the master order into individual orders and arrange for final shipping. Things can go to pot in a hurry. Good luck with the project and, if all the problems are solved in advance, it sounds like a good way to accumulate several good peonies.