The answer to whether you need an ISBN depends on your plans for the book. Each GriotBook comes with a ISBN that is registered to GriotBooks.com. This does not mean that we own your GriotBook; it means that we own the NUMBER to the book. If you decide to leave our company, the ISBN must be retired. ISBN's cannot be used again...PERIOD!
No If you are just printing up 50 copies for your family and close friends, then no you don’t need the ISBN or barcode. Although if you would like one there is no set rule that says you can’t, it’s entirely up to you.
Yes If on the other hand you plan to sell copies of your book and hope to get it into stores then yes, we would advise getting one. It will increase your professionalism, enable bookstores to contact you if they have a customer asking to buy a copy and also increase your chances of being noticed by booksellers and libraries. Maybe If at this point you’re still unsure whether the sales of your book will justify buying an ISBN and barcode it is possible to obtain one for a second print run, even if you didn’t have one for the first print.
Do you want an ISBN barcode with that? When an ISBN is purchased there is also the option of buying its barcode too, and if you are planning on retailing your book through stores I would strongly recommend getting one. The advantage of having a barcode on your book is that it can be electronically scanned by any shop that may choose to sell it. Enabling the price to automatically appear on the sales assistant’s computer monitor, which will only add to a smoother sale and a better record of how many books are left in the store.
It may be in your own interest as you want to sell books. If your books cannot be ordered and distributed by ISBN and if they are not listed in Books in Print you may find that your books do not sell: People will assume your books do not exist, and if they know they may consider it too much of a bother to handle them in a traditional fashion.