I have bought and sold audio books on eBay for the past 2 years. Here are my tips to help when selling audiobooks on eBay.
Try to get as much information in the title field as possible. Use as many of the 80 allowed characters as you can. Title search is the default and most people only search by titles, and do not click the 'search title and description' checkbox.
Try to list the title, author, reader, number of cassettes/CDs (X10 CD or X8 cass or X8 tape), duration of the book (8h 30m), the length (adbridged, unabridged) and the word 'audiobook'. You will generally not be able to get all these within the 80 characters, but the more you do the better chance your audiobook will show up when a buyer searches for it.
I would generally try title, author (surname only if you want to save space), X8 cass (as this gives the length of the book at a glance), 8h (as this gives the duration of the book at a glance) and add the others if space allows.
You can pay the extra money for the second line of text under the title but I only think this is worthwhile if you are planning to sell your item for a high price otherwise it will eat into your profits.
Make sure you get all the information (described above) in the item description as anyone searching with the 'search title and description' checkbox selected will find your item. i.e. If you could not fit the reader name in the title, make sure it is in your description as someone searching for a specific reader would find your item.
I would also add the publisher, the ISBN number and a brief description of the book including some of the character names. These are all to help buyers find your item when searching.
Used books (not ex-library)
If your book is not ex-library, make this clear in your description. Describle the condition of the item as accurately as possible. Mention the quality of the audio/recording and if there are any problems. Describe and wear and tear on the cassetes (tape and labels) or CDs (front and back disc surfaces) and the case. Try include a picture (or scan) of the item as this inspires more confidence in buyers.
The condition of the item will usually be well-used, it depends on the library and the popularity of the item.
Some people remove the library stickers, some don't. I'm unaware it it makes a difference. I think you need to accurately describe the wear and tear on the item as ex-library items have usually been well-used. As described above, mention the quality of the audio/recording, describe and wear and tear on the cassetes (tape and labels) or CDs (front and back disc surfaces) and the case as well as the library stickers (or marks where the library stickers have been). Try include a picture (or scan) of the item.
If you have described any problems with cassettes, CDs or the case the buyer cannot complain about the item not being immaculate when then receive it. People are usually OK and understand that they will not always get an "as new" item.
You can mark the length of your book as abridged, unabridged or leave the field blank. Some people leave the field blank to encourage more buyers to bid. I'd advise against leaving the field blank. Buyers can search for abridged, unabridged books or all, if you have left the field blank your item only shows up in a search for all.
It is always tempting to start your items at £0.99p as the eBay fee is low, however, unless you know your item is popular (terry pratchett, harry potter), rare, out of print and no longer available (although this doesn't always help) or don't mind if it sells for £0.99p I would advise you start at a higher price. I've generaly found that the less popular authors only get one or two bids and you can find your audiobook you bought new for £20+ can sell for 0.99p! A higher price may put people off bidding but this is always the dilemma on eBay.
Ex-library books tend to sell for less that books purchased privately from new.
I hope you find these tips useful. Remember everything above is my own personal opinion and has helped me sell audiobooks on eBay in the past. If you disagree with anything in this guide or have any ideas how it could be improved, contact me via My Messages with your feedback - kickflip720.