"Recruiters will do all that for me for free, and pre-screen everyone."

As a hiring manager, I've known a very few (but very good) contract recruiters who will actually do this. In short, most (contract) recruiters are sales people who are motivated to have a transaction occur.

As a hiring manager, I rarely find that there interests are aligned with mine.

Having said that, I am also not sure if this pricing works or not.