Asking "how much should I expect to pay for editing, design, and layout" is like asking, "How much should I expect to pay for a software developer?" It depends on the expertise and experience of the person you're apt to hire, the size of the project, and a number of other factors. Not the least of which is "How awful is the text to begin with?" and "How much formatting is necessary?" and "How much of a PITA will this client be?"
That said, I'm a professional editor (as well as writer) who has bid $4,000 or so for a project that sounds similar to what you describe (though that was a full-length book). I'm an eensy bit well-known ::cough:: so I expect you can pay less; depending on the expertise of the book editor, you might need to pay more. (And I'm too busy right now, so that's not an offer of assistance -- just a ballpark number.)
That said, I'm a professional editor (as well as writer) who has bid $4,000 or so for a project that sounds similar to what you describe (though that was a full-length book). I'm an eensy bit well-known ::cough:: so I expect you can pay less; depending on the expertise of the book editor, you might need to pay more. (And I'm too busy right now, so that's not an offer of assistance -- just a ballpark number.)