Do it thru Disney, whether on the ship or on Castaway. It will be clean and the price will be as advertised.
We did it once in the Bahamas (begging child, grabbing ladies, etc). The sign advertised $2 per braid. After doing one braid, the lady wanted $10....excuses...she has long hair (not quite shoulder length,,,I'd call it "just below chin), the beads are extra (pony beads are about 2 cents each at any craft store), etc. I paid and got the heck out of there fast!