I have 5 MP3-CD audiobooks by Donita K. Paul in excellent condition in their cases.  They can be played on your computer or in a CD player that has MP3-CD playback only.  PBS rules say you can't post audiobooks that have to be played on a computer.  One of them is in the PBS catalog which I will link to so you can get an idea of this storyline.  I'm offering all 5 for 2 credits.  They are marked as originally $19.99 each

They are: (Dragonkeeper Chronicles)

Dragonspell ISBN  1423392558

Dragonquest  ISBN 1423392612  http://www.paperbackswap.com/DragonQuest-DragonKeeper-Chronicles-Donita-K-Paul/book/1423392612/

Dragonknight  ISBN 1423392671

Dragonfire  ISBN 1423392736

Dragonlight  ISBN 1423392795

Please PM me.

FWIW, I am posting this response to the OP simply because I want to clear up a misunderstanding of the rules for others who may be reading this. 

"PBS rules say you can't post audiobooks that have to be played on a computer."

I believe you have misread the rules - it is actually books that must be read on a computer that are not allowed and this rule is specifically addressing e-books and CD ROMs, not MP-3 on CD audiobooks.  The only audiobooks not allowed are, as the rule states, burned copies such as from an original CD or from a download such as from Audible.com or a library download.

Not allowed:

• CD-ROM books/e-books (books that must be read on a computer) (highlighting is mine)
• Burned copies of audio books

MP-3 on CD audiobooks are postable/swappable here but often times the ISBN is not recognized by the system and they have to be posted as without an ISBN.  That being said, in my experience, MP-3 on CD audiobooks are not as easily traded here as I have found a great number of people are not familiar with them and do not have MP-3 compatible players.  Personally, I love them as I listen to everything through my iPod and transferring an MP-3 format CD to the iPod is much easier and less time-consuming than an audiobook containing multiple CD's that have to be ripped individually to the computer first.