Etiquette

My friend is getting married in October and I am a bridesmaid. I live four states away and the travel costs for the wedding is going to be very expensive. My friend is having a shower in September, which means double the travel costs. When I told her I didn`t think I could afford it she got mad and said that she thought it was a "requirement" for bridesmaids to be at the shower. Is it? To make matters funny.......this is the most non-traditional wedding I have ever heard of....we are walking down the aisle to the Love theme from Edward Scissorhands. Am I being ridiculous?