You can score a ball joint press from Harbor Freight for $30 - Autozone is nuts for wanting a $99 deposit to use theirs, it's the exact same unit.
Make sure you've got everything lined up just right when you go to push 'em in/out, as they're pressed in so snug that they will flat-out refuse to budge unless you're dead-on straight. That, and it'll take some playing around to figure out exactly how the adapters on the BJ press tool work, and it's a friggin' bear to crank those things in/out of there, so be sure you've got some sturdy wrenches - I actually broke a 12" long Craftsman in half while doing mine.