I agree that it's not cost effective to manufacture your own. I think line would work though. The jib halyard is never supposed to take load off the forestay. It just keep the wrinkles out of the leading edge.
I bought a spare to have in my parts bag. Not too expensive and I figure I'll need it eventually anyway.
I have one complaint with this product. The swaged (sp?) on shackle pin is not a "keeper" pin. The swaged loop is small enough that you can't get the shackle out to replace it. You have to buy a new setup or cut the wire, replace the shackle and reswage. I know it sounds petty but this drives me nuts! It's such a small pin. One day it's going to slip while standing on the bow with cold wet fingers...
Todd
TheMightyHobie18, MN