I'm very new to PBS and I have a simple question. I have two copies of Under the Dome hardcover and I think there are a few people waiting for this.These are big books. Is it still $2.38 to mail this by media ? I have not used the PBS wrapper service since I drive by the post office every day . thanks for any helpful replies.

$2.38 up to one pound, 39c per additional pound.

I would weigh the book in whatever packaging you might use to send it and then look up the postage on the USPS website.  There is a postal price calcultor there.  Most likely it would only be about $3.00 to mail.  And no you don't get extra credits for mailing a heavier book. 

If you don't have a scale to weigh it you can find the weight on Amazon.  The PBS weight isn't always accurate.

According to Amazon, the book is 3.8 pounds. That would translate into a 4 lb rate of $3.55

The book is selling for $7.49 or  more used.

*This is only a ballpark figure*