Even though books are heavy and bulky, sending them long distance to friends as a gift, or to yourself when moving, does not have to be expensive. If it's not imperative that your books arrive quickly, the cheapest way to mail books is by sending them Media Mail through the U.S. Postal Service (USPS).
A 6-by-9 inch paperback book with 226 pages inside a padded paper envelope weighs 14.4 oz. Ten such books in a cardboard box would weigh approximately 8.5 lbs. Let's say for example that you wanted to ship both of these packages from Seattle to Los Angeles.
According to the USPS website, the price to ship your packages via Media Mail to a destination anywhere in the United States is based solely on the package weight. The destination's ZIP code is not a factor. For a package of less than a pound, you would pay $2.38; and for a package of less than 9 lbs., you would pay $5.50. You can add delivery confirmation for $0.80 per package. Additional tracking services are also available. The drawback is that Media Mail is not available from the Automated Postal Center (APC) located in the lobby of most Post Offices.
The price for Parcel Post is determined by both weight and distance. In this example, you would be shipping to Zone 5. A package less than a pound would cost $4.90 to ship, and a package of less than 9 lbs. would cost $12.55. You can use the APC to ship via Parcel Post, unless you require additional services, such as Delivery Confirmation.
You could fit the single book into a Priority Mail Flat Rate envelope and mail it for $4.90. Ten books of the example size would not quite fit into the medium size Flat Rate Box of 11 by 8.5 by 5.5 inches, so you would need a large Flat Rate box, which would cost $14.50 to ship to a domestic address.
If you prefer to use a private carrier, you could ship your package via UPS Ground, which automatically comes with advanced package tracking. Your package that weighs just less than a pound would cost $9.73 to ship from Seattle to Los Angeles, a significant increase from the USPS. However, your package that weighs less than 9 lbs. would cost $13.01, which is less than Parcel Post plus Delivery Confirmation.
The cheapest way to ship a big heavy box full of books is via the USPS.