Try this site.
Matt Clement is (was?) a college student that was making the interface cables for FMS to put himself through school. He sells the older style cable (with the round connector) for about $25 shipped, and includes FMS on a CD. Don't know for sure if he's making the newer connectors, but he'll be reasonable if he is.

http://www.mattclement.freeservers.com/fms/fms.html

Dennis-