Pretty much the same as everyone else.
1. Stay as local as possible
2. The studio showcase events can be your friend. I dance 3/year, plus a comp (though I did do an extra comp this year, one I was able to easily drive to). I don't know about the chain studios, but generally there is only an admission fee for the ones I do (usually big parties w/dinner at Christmas, more casual in the spring). At least this way I get a unique routine, everyone loves to watch partner and I dance (and I'm not stuck dancing on a freaking Thursday afternoon, like the Rhythm people get stuck with at comps), and I don't feel like I am throwing money down the drain on lessons I'll never use.
3. For this amount of dancing, I rent costumes, though it can be difficult for the non-size-2 crowd to which I belong.
4. Stone your own! I've made some passable showcase costumes for quite reasonable amounts from things I've bought off the rack or ordered from dance stores. Ask around if anyone has something you can borrow.
5. Dance am-am if you can, but in my neck of the woods, amateur men don't grow on trees. And I don't think I could give up Mr. Pro at this point!
6. Sacrifice elsewhere. I haven't bought lunch in ages, and rarely eat dinner out (though some of that has to do with numerous food allergies). I live in a dump for now. I keep my windows open as much as humanly possible to save on energy. You will have to pry my Starbucks soy latte out of my cold dead hands though.
7. Stick to one style if you can stand to. I'd love to get started on smooth but until I win the lottery or find my sugar daddy, I'll stick with Rhythm since I only can afford one lesson/week (or every other week).
8. Something I haven't seen yet- a female instructor I know held 2 short (1 hour I think) workshops on hair and makeup for the gals (15 or so signed up so she split it). She charged $20, had everyone bring their makeup, accessories etc., and we had a big ol' girl party learning how to properly do makeup, good colors for our skin and costumes, and the harsh lighting and such. She had small gift bags with a few things we might need for future use (clear lip gloss, eyelash glue, etc). Perhaps a suggestion to put forth if you know someone who might do something like that.