I did a search on that Yahoo group you mentioned and even though I can't join the list, I was able to do a search and found a few posts about those screws (Dzus as they're called). One poster mentioned a company called Southco, http://www.southco.com/landingpages/dzus/ but after reviewing their site, they only sell through distributors.

I looked through their distributor list and as luck would have it, there is one just a few miles from where I work!! I'll stop by this week with my Dzus in hand and see if they'll sell me a few. (Hopefully they sell to individuals and not just businesses in quantity.) If I find they will sell me a few (I want some spares), I'll post again so that others can know where they might find some.

Hopefully they're much lower than the dealer's $20.

Thnx, Deb