Isn't it always the case that the people you recruit make the business! If it is possible this is even more relevant when you are starting a new development project in a new platform or technology where the people you recruit (either contract or permanent) make or break the project.

Frankly in our experience the agencies don't all do the best job in whitling down the applicants. Once we have taken the time and fully undertood and agreed the attributes of the people you need, we can help at all stages; interacting with the agency, ensuring candidates are of the required quality, and technical reviews to ensure that the candidates know the stuff you need them to know.