Nick did you not mention elsewhere that it was a church
project ? It might surprise you how much seed the participants might actually have from their own seed saving to begin with . Here's a thought to contact the Seed Sanctuary of Canada,
http://www.seedsanctuary.com/ for a membership you can grow out selected seeds , growing them out, taking notes , keeping some for your self and donating some fresh back to the seed bank . Your group might be able to negotiate something growing varieties they really need continued and grown out this year ? The endeavour also may help retain genetic biodiversity for generations to come.
8 feet high is pretty ambitious . Mine is 50 feet long, 6 feet wide and about 3 feet high to date of layered trimmed branches to date , nothing covering it as the
wood and brambles die off. Ludi, it looks like a beaver dam across my front
yard between the house and the street, you can imagine what my upscale neighbours are thinking at this point .