Id be a buyer of a few hundred if you can get the price down to a rate comparable to LEDs (generally $0.02-$0.05 each)
Problem is, it's unlikely we'd ever get there. LEDs have thousands of applications, so they're produced in quantities far beyond what we're talking about here. This is a specialized item, with a specialized mold, manufactured for a unique (and smaller audience).
From what I've seen elsewhere, we might get as far as $0.10/each. I hope I'm wrong, but it's worth noting the market at play here.
I get that, I really do. But for 15 cents a piece, I can get an LED and a socket and just have quick change LEDs. Then If I find myself using one color to the exclusion of others, instead of having a drawer filled with specialized items with a unique purpose, I have drawer filled with sockets and LEDs.
Or if I really wanted to, I could just buy the "lamp shades" directly from OPs link for 7 cents ($0.07) a piece.
ETA: I guess my point is, whats the point of a group buy that doubles the price of the item? isnt the point of a group buy to get it cheaper than "store" price? plus if I buy it on own, it comes with a free storage box.