As a data point I'm reading some series I enjoyed the first 2 volumes of. I just picked up the next 7 ones because they were there and each of em were ~$5. Wouldn't have done that if they were $30, and I'm not guaranteed to get to the end!
Well it doesn't matter. Even if you compare to books that are newly published, new hardcover fiction is not $43-54. Typical is about $30.