I'm amazed at how much discussion this project has garnered. It's almost worth its own thread.
Berkshire Junction claims the product is not rubber. And yes, I imagine it's available at craft stores or someplace. The EZ-Line spools are 100', so for roughly $10, that's still a fine deal for me, since I know what I'm getting (versus trying to find a "similar" product and maybe being disappointed).
The product does come with a UV warning. Yep, someday it probably will turn brittle. But then, so have my SuperTrees in much less time, and that's with longer than the recommended preservation soak. As DKS mentions, lots of other things will also decay with time under UV. It is what it is, and I'm not averse to trying an otherwise neat and fun product based on an unquantifiable risk of long-term degradation.
As for dust collection, dust is a problem on everything, not just wires.
Chris, I'm thinking about when I restring those green lines with gray, moving them in from the corners of the cross-arms an insulator.