Sex of baby in ultrasound?

My husband and I are struggling very bad. We are actually in the process of moving in with my mother to save some money. I am dying to know the sex of the baby but my medicaid expired and I still haven't been approved for it again. My appointment is tomorrow but they are charging me around 350 which we don't have. Would a hospital do an ultrasound? And would they tell me the sex of the baby? I'm only 18 weeks but I'm going to have an early babyshower because my nieces are visiting us and the really want to be a part of it.