Ok, this is a really, really old thread, but since I recently just had the same exact problem, I thought I'd update it for anyone else in the same situation.
I searched just about everywhere for those little springs and was about to give up and spend the $15 on whole new wiper arms, when I found perfect matches at a local Sears Hardware store. Not a regular Sears, but one of those hardware-only places. They've got racks and racks of little gizmos, and a pretty good selection of little springs.
So instead of spending $30 for new wiper arms, I spent $2.00 for new springs. Ahh, the small victories.
'81 CJ-7, 175,000 miles
Stock 258, SR-4