I was thinking the same thing, Laura. Have you tried the old ones that look like strands of rope? Heck, I don't even know if they still make them. But that's what we used when I was a kid. Well, scrap that- they showed up on the Professional Choice's site as mohair! LOLI've never seen a leather western cinch...
http://www.profchoice.com/htmldocs/prd/western/index5.html