What should I wear to my court house wedding?

Me and my fiance are getting married next month. We were planning on waiting but then last night he said he didn’t want to. So today, I’m frantically searching for someone to tell me what to wear at the wedding. It is a court house wedding and I really don’t think a wedding dress is appropriate, and I don’t have that kind of money to spend on one. So a sundress maybe? Or what. I would really appreciate some ideas and opinions.