I always liked Strunk & White a lot - regardful of my high school teachers' reverence for it and regardless of how much I followed its advice. I recently reread part of this book for fun, which I regret with the sadness of watching classic pillars crumble. This is an example of a text that doesn't hold up after college linguistics training (one crutch for another?) or developing expectations for principled empiricism. My criticism is mostly for grammar reasons, and I honestly thought I was alone on this until I read 50 Years of Stupid Grammar Advice (via Language Log).

I definitely still think there's affordable style advice in there, and I'd bet it's yet a decent educational resource (though I'd imagine you can find the good bits elsewhere in a more accessible form without the grammatical shenanigans).