Thanks to one awesome neighbour, I have a new spirea (smallish and pink-flowering), some gooseneck loosestrife (which is apparently apt to be thuggish, so I'll have to plant it in a pot, I think), an astilbe, and some silver deadnettle.
Another awesome neighbour is redoing her driveway and has offered to share the cost of delivery for crushed stone and sand, making the aggregates for the spiral walkway a lot more affordable.
The bricks, meanwhile, have been found and delivered! Cobblestone interlock pavers, actually. They were more expensive than what I'd originally been hoping to spend, but they are so gorgeous that I'm thrilled to pieces anyway. I did a dry run this weekend and totally should have taken pictures...for my absent-mindedness I will just have to wait for a few weeks until we can get it done for realz.