Renting Dresses?!?!?!?!??

So as alot of people know, I am getting married. We have been engaged for over a year now and just started planning. I have 2 bridesmaids, Rhonda (maid of honor, I have know her since middle school and she has been there through everything and stuck by my side since then) and Heather (I met her a little over a year ago in nursing school, she is one of my best friends, she is a wonderful mom of 2 and a great friend)! Well both of them have been there for me through alot and know everything in my life! I decided that I wanted their help in picking out their dresses and let them have a say because I want them to be comfortable in what they are wearing. Well this weekend when mom and I went to look at my veil (which I LOVE) and to make a payment on my dress I started looking at the bridesmaid dresses. Mom made the suggestion of renting dresses (that's what she did and they were pretty), she said that she wasn't sure if they still did that. GUESS WHAT!! They do! Here is the thing I am worried about and so are my girls, and it is what if they don't fit and what if I don't like the colors. They said that they will do whatever I want to do. I really want T-length and 2-toned colored dress. I guess I need to keep my eyes open and keep looking, but do we rent or buy????