Most local studios have a wedding package that isn't too awfully expensive. It's basically them walking you through some basic steps, adding here and there, and making your own short wedding dance routine.

I'm no marriage counselor, but you should probably not jump into a marriage with pre-existing financial woes (and if you do, for god's sake, take the pill, Lol). Cut corners on the wedding. Have a simple, pretty ceremony, do the decorations and stuff yoruself, then splurge on dance lessons. All that crap you use to decorate with will wilt and die and be thrown away- ballroom lessons are, like, so totally, you know, more forever, and stuff, than diamonds.