How much does a pregnancy ultra sound cost out of pocket in Chicago?

I am currently unemployed and uninsured. I am getting married in 2 weeks and will then be added to my husbands insurance. I just found out 2 days ago that I am pregnant. I was just going to wait until we're married to go to the doctor but last night I had severe lower right abdominal pains that have dulled today but they are still there. My symptoms suggest possible ectpoic pregnancy so I need an ultrasound but don't know how much it will cost or where I should go for it.