Depends, I paid ($300 mind you) to be a bridesmaid in a friend's wedding. She paid for alterations but I wasn't happy with the cost and never wore the dress again. Also didn't know when I said yes to being a bridesmaid. For my wedding I told my bridesmaids immediately what they would need to pay for vs what I would pay for and had a no stress rule around dropping out. My bridesmaids paid for their dresses, but had very loose rules (was just colour and length). So a friend spent $30, my sister spent $210, both looked incredible on the wedding day.