If you are an Indie Author, you know that publishing has a lot of costs. You might have been able to cut some by having beta readers act as editors, or exchange services, etc. One of the things that cannot be avoided is the cost of ISBN's, if you plan to go wide. This means having your books available through bookstores and libraries. Amazon and Ingram Spark offer their own way to get a free ISBN, on paperback and e-book formats, but this will keep you locked into their system. For example, in Amazon's KDP, you'll show up as 'Independently Published' and libraries will not be able to access your paperback, and most bookstores will not sell your book as they do not offer the same trade discount as standard publishers.
By owning your own ISBN, you set up your own publishing name and company, and then you can take your books through any system you want. What tends to stop a lot of people is how expensive ISBN's are in the US. You have to go through the Thorpe-Bowker site and they are $125 for 1 and $295 for 10. ISBN's are cheaper in other countries, like Australia, but you technically have to purchase the ISBN in your own country if you're going to own it.
Which is why I'm offering this. I own a publishing company that was founded on accessibility. If the thing stopping you from publishing is the cost of ISBN's, then I've got you covered! You will just show up as published under one of our imprints (the imprint depends on your genre) and retain your rights and indie publish per normal so you can go wide.
The cost is $9 per ISBN, this covers the ISBN and card processing fee.
If you plan to have paperbacks OR hardcovers in Ingram (stores and libraries) and Amazon (KDP) but eBooks in Kindle Unlimited you will need 1 ISBN
If you plan to have paperbacks AND eBook in Ingram (stores and libraries) and Amazon (KDP) but not Kindle Unlimited you will need 2 ISBNs
If you plan to have paperbacks AND hardcovers in Ingram (stores and libraries) and Amazon (KDP) but eBooks in Kindle Unlimited you will need 2 ISBNs
If you plan to have paperbacks AND hardcovers AND eBook in Ingram (stores and libraries) and Amazon (KDP) but not Kindle Unlimited you will need 3 ISBNs
If you haven't decided which route you are going yet, you can start with one ISBN for paperback and get more later if needed.