My fiancé and I are having our reception in the loft of a barn.

We were just told that it's required that we have a dance floor in the loft. I found this picture on my venues website to give you all an idea of where it will be. It looks like this couple has some type of dance floor, but I'm not sure what.
Anyways we didn't know or realize that is was required, so it wasn't budgeted out.
SO we aren't able to afford renting one, it is going to be about $300-400
Any other ideas as to what we should do?