Independent publishers and authors in the US are responsible for acquiring ISBNs for their books by purchasing them from Bowker, the US ISBN Agency (www.myidentifiers.com); if located in the US, you can also purchase ISBNs through IngramSpark for $85 each by selecting “Click here if you would like to purchase an ISBN (an ISBN is required for distribution)”, during the title set up process. Bowker sells a single ISBN for $125, 10 ISBNs for $295, or 100 ISBNs for $575; therefore, it’s always advisable to purchase ISBNs in bulk, unless you are certain that you will use only one to three ISBNs for the entirety of your publishing career. ISBNs purchased through IngramSpark are non-refundable and as the publisher, you will own the ISBN.
Be sure to use the same ISBN for your book in all sales channels. Listing the same book with different ISBNs on multiple distributors may confuse retailers and consumers trying to purchase your book.