What would make a  very thin 5 x7 inch paperback  book cost $2.92 ??  It was mailed media mail and that sounds excessive to me!

The weight might have been wrong in the system. If you are using online postage or just adding stamps, you can't trust PBS weights.  Books get issued in multiple editions for 1 ISBN which might have different weights, people enter data incorrectly-either on PBS or Amazon which is where PBS gets a lot of it's information.

Either that or the postal clerk didn't put it in as media mail but as 1st class and that was the charge for whatever that book weighed.

As Mary said, the PBS weights are so often wrong...and if you aren't using a scale to enter accurate weights that is the sort of thing that happens. The other thing is the paper quality...if this is, for example, a book of art prints it would be printed most likely on a coated stock and that paper is very heavy. It is all a matter of weight in the end.

Because the weights are so often wrong on the PBS site, I always take my packages to the PO to mail and almost always they'll find that either the postage is wrong, or if I ship the package first class instead of medial mail it's cheaper.  I had one the other day that PBS postage was marked over $6.00.  Don't remember the book, and don't remember the postage, and don't know how to fix it after the fact.  Pat

If you find that the weight for a book you are mailing is wrong, PLEASE correct it by clicking 'More Options' in the book details page and choosing 'Edit Book Data'. From there, you just have to enter the weight in POUNDS (so for instance 8 oz. will be 0.5 lbs.), enter the reason for editing (if you are weighing the book yourself, just say so) and click 'submit'. A person from the Book Data Correction group should then review your entry and approve it.