Check some of the various ballroom wear and shoe websites for clearance deals on "bigger names"- by that, I mean Supadance, Elegance, Werner-Kern, International, Freed, I think Ray Rose, and so forth. Sometimes you can find a $150-shoe for around $65-$99 or so.
If you're going to buy "cheap shoes", just get a crappy pair off ebay for about $30 (365buys or some of them have the low-low-end shoes that are okay for maybe a couple hours a week for a few years), but if you're going to actually *dance* in them, suck it up and buy the real ones... AFTER you sit down with several and try them on.
If it's your first pair, you want to make sure that you get a good idea of how they fit instead of guess-volleyshoe back and forth in the mail. Guys are typically worse about getting them too big, but women do it too- the street-shoe size we're all accustomed to is WAY different.
I think it's dancehappy.com that has a clearance section for shoes for a hundred bucks or so? Give them a try. Otherwise, watch Ebay and the stores (My Little Mall has a few Elegance left) Like a hawk, and you might come out with a deal.