what about a make-up box with sissors, combs, brushes, hair dryer, spray bottle all in side.
You could make all the supplies out of fondant.
even add a curling iron.
I have seen sewing boxes similar to what I am thinking.
Not sure on how to put it all together, but I am sure someone else could help you with that. 
Good luck!
you could possibly do something a little easier and try to make a cake that looks like a head with long hair on it? or cut and shape your cake to look like a hair dryer or something.
Check out this link. This lady michelle did a hairdresser cake. It is at the bottom of her page.
http://www.michellecakes.co.uk/portfolio.html
If you are like me and not to adept at fondant, how about a bright colored funky Pricing board. Use your sense of humor. ie:
Haircuts........with scissors..........$10.00
with conversation...$ 15.00
Give it a cool Salon name and have fun with it. Use your imagination to decorate it up with iced haircurls, etc.
Hope this helps
RaeMarie
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