I just visited a great little shop out here in the suburbs -- America's Market. Fascinating stuff -- a blend of old favorites you thought had disappeared (Teaberry gum, for example) to gourmet delights (including meats and sausages from the Elburn Meat Market). They specialize in "unique foods from around the U.S." -- hence the name.
I got chatting with the owner, and he mentioned that they'd had a big root beer tasting event last week. I'm not a big fan of root beer, so I didn't take any particular notice of the range of root beers, but being able to give a tasting suggests some sort of variety. They carry a good number of sodas, including Mexican Coke with sugar, so it seems to hold out hope for your root beer.
You may at least want to call to see if it's worth the drive.
America's Market
9 Huntington Lane
Wheeling, IL 60090
847-850-2563
Todd Schultheis, proprietor
(for those who have attended the French dinners at Berutti's, or who at least know where they were held, this is just around the corner -- next to I Am Siam -- if that helps you place it)