There are better ways to spend $100. The only thing the alignment shop will do is adjust the toe in and scratch their heads as to how to adjust the caster. There is nothing to adjust on the rear end - this isn't a coil suspension with adjustable control arms. Everything is self centering and self aligning when in proper condition.
If a YJ is crabbing you got damage to the suspension or to the frame, or both. There is no way on God's green Earth that an alignment shop will fix a "crabbing" problem on a leaf sprung YJ for a flat $100 fee, all potential parts and labor included.
I mean sure, if you aren't comfortable with a wrench you have to pay the premium to have an experienced person do the work for you. But there are many of us quite competent to be able to inspect a leaf sprung suspension to verify it is squared, and to be able to turn the tie rod with some vice grips to adjust the toe in.
And besides, that $100 is better spent towards some brews and good food that can be enjoyed after we get done doing our own repairs.