Bridesmaid issue!

Alright so my problem! When I first got engaged I was so excited about picking my bridal party. Well I told my cousin Lisa that she could be a bridesmaid. It just hit me who is going to pay for her outfit (dress and shoes) which is going to be around $150.00. She does not have a job, has a child, and her boyfriend really does not bring home much. Basically she is living off the government but she is trying to get a job.
I really want her in the wedding but I can not afford to buy her dress. If I did that it would not be fair to my matron of honor (Stephanie) and my other bridesmaid (Christina). I am already going to buy Mariah outfit which is her daughter. What should I do? Find someone or pay for her outfit?
If only I would win the "One Love Contest" then things would be solved! The whole bridal party would not have to pay for their outfits! Then I could have another bridesmaid that is if Michael would go with it. He is set on three members each. I think this is because he really does not have many close friends.
Please vote for me:

David’s Bridal "One Love" Contest Sponsored by David's Bridal