Here's an idea:
http://costumepop.com/adult-costumes...d-king-triton/
Ursula came to life by modifying an old prom dress into a skirt. The octo legs were sewn from a 3 sided pattern to give the tentacles dimension and the abitlity to stand up almost by themselves. They were stuffed with light weight Cluster stuff and then sewn to the inside bottom of the skirt. The tentacles were then sewn to the outside of the skirt at the point where they curl outward. The top of the costume was a long sleeved lavender shirt with a black waist shaper and a strapless bra on top.