I think I got answers to all of our questions about the Adopt-a-Stone. Hopefully you're all still interested in doing this!
If I include a list of all donors, each donor will receive a receipt for tax purposes. Certificates cost the organization $5 apiece to print and mail, so that essentially comes out of our donation.
Since there are nine of us, there's not much difference between $200 or $250. I'd suggest either a $200 Prism stone ($22 each) or a $250 Berm Coping stone ($27 each), since those are both visible as you ride through (see the diagram
here). Any preferences? Once we decide, I'll send out a pm to each of you with my address so you can send a check to me, which I'll then forward to the organization.