If you're talking about using a trained voice actor, yes, they will cost an hourly rate to do this, which is reflective of the care and training they put into their craft. One should also expect that they don't simply press record, and then do an entire read through. They will go back and try different takes on segments
If we're not talking about a trained voice actor, you may want to look at some thing like LibriVox, which is entirely volunteer run on public domain works, and while the efforts are appreciated, the quality is noticeably different.