Anyone out there have specific experience building Shelter-Systems domes?

I am currently engineering from pictures and friends smaller domes a 30' Shelter-Systems design. This is a PVC dome using 1" pipe in 5 foot and 3' lengths. It is a semisphere design and as a geotensic structure uses the frame to pull the skin ourtward from it's internal attachment (exoskeletal).

I have been looking at material for the covering.. and think I am set on Thoroshield 8000.. the stuff is amazingly strong and uber-lightweight.. but not as breathable as Tyvek Supra.. which is the bomb for sure. I will be creating the skin from sectionals as the dome is constructed and then interleaved to create overlapping sections for waterproofing and beathability.

My question concerns the cost for the anchors.. they are the most expensive part.. $150 for 100 of them.. it is more than the PVC itself. What tarp anchoring devices do people have experience with that are highly functional and low cost?

Pictures in the tribe home photo area.. consisting of straws.. 1/16 scale model.