Plus Size Bohemian/Hippie Style Long Dresses??

Ok so my sister is big and beautiful and she saw these "oh so cute" Bohemian/Hippie style long dresses at Target.. The catch.. They were in the Junior Dept and she is an adult size 18. Where can I find one for her? Please don't say ebay or Old Navy...Have yall seen the dresses I am talking about at Target?? SOOO CUTE!!!