Spirit, what else is new, is having yet another 1 cent sale! And you can actually book tickets for basically nothing more than taxes. Bo, our dedicated fare hound, has been researching and posting these fares all day. Thanks Bo, we know it's tedious work (he's actually been seeing which fares you can actually fashion into a logical round-trip, since these fares must be bought round-trip and they're not always available).
They also have some cheap $8 one-way fares. Sometimes seats are only available in one direction and not the return, but even if you have to pay full fare the other way you'll still save money. Click here to see the sale.