Help! Need to find a dress!!

I have a wedding to go to the last weekend of February. I'm 20w now and I can't find a dress to wear. I've tried destination maternity and of course they have some beautiful dresses but they are $150+. I don't want to spend that much money on a dress that I will wear only once. It doesn't need to be a long dress... I think a cocktail dress would be fine. Any suggestions where to find a dress?