The first thing to be aware of is that there are three basic paperback formats; A, B, and C:
- A-format is the most common, otherwise known as "mass market" paperback, generally 110mm wide x 178mm high. These books would commonly cost from AUD $8 - $16 brand new.
- B-format paperbacks are associated with literary authors and prestigious lists, measuring 130mm x 198mm. These books would commonly cost from AUD $18 - $26 brand new.
- C-format, otherwise known as "trade" paperback. Trade paperbacks are 135mm x 216mm or larger. That is the same size - and possibly the same paper - as a lot of hardbacks. These books would commonly cost from AUD $28 - $36. (Note: In the US agents referring to "trade" actually mean B-format.)
Prices are more difficult to decide for books which are rare or out of print, but you don't need to be an expert to get a rough idea of value. Plug the ISBN number or the Title of the book into a search engine like Google and see what comes out. If you are looking at a book as a collectible then you need to do more thorough and specific research on the Title and the Author.
By this stage you should have a general idea of the relative value of the book you wish to buy. You will also know what questions to ask the seller if you need more information before bidding or buying. It may help you pick up a bargain, or save you from paying more for a book than you would actually pay buying it new in a bookstore - caveat emptor.