There is still a lot of question in some people's minds about what the difference is between indie publishing and self-publishing. Indie publishing and self-publishing can sometimes be considered the same. However, as a self-published author, you are normally paying a "vanity" press, which charges you for every process. Vanity publishing often means that you pay and pay and pay for the privilege of someone else making money on your work. They operate a lot like a traditional publisher with the exception that they charge exorbitant fees. They also keep the lion's share of the profits giving you a smaller "Royalty." Vanity presses earned their reputation as using sub-standard processes, which made bookstores refuse to handle them.
Indie publishing means that you are in control of your manuscript. Unlike the "vanity" press, you are not bound to pay for services that you don't need. On the other hand, all the services that you need, you have to find on your own. Although you must do all the work from beginning to end, there are people who will help you with each phase of your publishing process. Being your own publisher may seem daunting, but understanding that you own and control you material makes up for it. When you get published through any other means, you do not own your intellectual property: the publisher does. If you are not in control of the entity that purchases the ISBN, you are relinquishing your work to someone else. Each title requires its own ISBN, because this is the "International Standard Book Number." Without the ISBN and its bar code, you cannot put your book into book stores or just about any store that codes the bar code into inventory and point of sale cash registers. So the ISBN is a huge part of publishing your book.
Here's what I want you to understand: that ISBN is connected to the ownership of the material. The publisher owns the ISBN, which translates to the publisher owning your intellectual property. If you want to use that material for another product, you cannot do it! That is, you cannot if you aren't the publisher.
Creating multiple products from one collection of material makes the most sense. If you are an entrepreneur, in particular, you want to create and recreate as much as possible!
Becoming your own publisher is not as difficult as it might seem. You can be published through CreateSpace.com and choose your own ISBN and own publishing "imprint," which only costs $10. On the other hand, you can pay $125 for one or $250 for 10 ISBNs. You can get your book printed by an on-demand printer, which also is your fulfillment agent. LightningSource.com may give you other advantages, such as higher quality paper or different book sizes, including hard cover book options. As a publisher, you get to make all the choices. No one is making you, the round peg, fit into the square hole. You are in total control!