It was definitely harder than we imagined. We first tried calling a list of the agencies and some of their rates were way over our budget. We found a couple of agencies to go with and when we finally settled with one, the models that showed up looked nothing life their portfolios!
So we moved to another tactic, searching on the internet. Model Mayhem was the best, you get to see the portfolios of models from all of the agencies and set up a casting with them directly. Our first two fittings went great, and I can't imagine doing it any other way.