Hi
My name is Thalia, and I am contacting you because I believe you have a very interesting project. I am an absolute fan of Polyvore and I would love helping you creating your sets; and even though my Freelancer profile mentions that I work more in travel and coordination, I have a degree in design and I am currently studying digital marketing.
I checked your website and I think you have a lot of material to work with, and it could be really nice to match them with the other items you mention (hats, sunglasses, dresses, etc). About the cost for the 100 sets, I think it will depend on how many hours it could take to create them, specially searching the matching items, but if you have an idea of these websites I believe it would be so much faster.
Please don't hesitate to contact me if you have any questions, I would be really glad to hearing from you.
Best regards!
Thalia