How much did you spend on your prom dress?

I'm trying to see how much others spend on their prom dresses so I know which one to buy. Originally I was planning on buying one under $100 but the cheapest of my dream dresses is just under $200 and the rest are in the $300-$400 range. I find this to be a bit extravagant but would like to see if it was normal for other girls to buy something this expensive. Also this will be my first and last prom so it's not like I'm buying that much every year.