I lurk here mostly.
I talked to a manufacturer on getting them made and after a month of contact they went silent. I was quoted between $3 and $11 apiece depending on quantity. I was asking for a run of 5000 pieces because I figured that would be enough to make a setup worth while.
I also would use hundreds of them, I was buying them directly from "Big Green" right up until they were sold at bankruptcy auction.
Currently that spring costs me more than the other materials combined that I used to make my part.
