Some books, like JK Rowling's first Harry Potter book, are not rare but are quite valuable if it is a first edition. There are thousands of Bibles from the 1700s and 1800s that can be bought for under .00.
If you can find a rare book in mint condition, crisp, unopened or uncut, those books tend to be a lot more valuable than those in poor condition, such as books that have broken spines or have writing on the pages.One of the main exceptions to this rule is if the book was owned by someone famous who wrote in the margins of the book.Some things that might make a book rare include: The best way to find the rare book values for books you already own is to do some searching online to see what the going rate is for the book you have.Generally it's a good idea to toss out the highest and lowest numbers you find and take an average of the rest to get an idea of how much you can expect to ask for your rare book.Condition is a very relative thing, so the prices you find online will probably vary widely.
If you're not sure how to rate the condition of your book, there are industry standards to help you figure out if your book is in good condition or fair condition.
The absolute best way to find out the value of your particular book is to find a rare book appraiser who can look at your book in person and determine its value.
Rare book values are very subjective, and can vary widely depending on what the local market will bear where you are trying to sell your book.
It pays to try to get a couple of different appraisals before you decide to sell your book just to make sure you know all you can about the book and its potential value beforehand.
In addition to using various websites to find the going rate of rare books, there are also websites that will provide you with an estimated value of books.
Value My Stuff provides valuations for rare and/or collectible books.