When time is less of an issue than cost, both printed matter and books can be sent by one of the following reliable, affordable mailing options:
Library Mail can be used for sending educational material (books, papers, diskettes, tapes, or scientific specimens) from, or to, an educational institution. Rates are based on weight and size.
Media Rate (formerly known as Book Rate) offers the best rate for sending small and large packages containing books. Rates are based on weight and size, and are the same as Library Mail.
Parcel Post offers the best value for shipping items other than printed matter or books. Prices are computed by zone.
You can calculate postage rates at https://postcalc.usps.com/