Yes. If your book does not have an ISBN, (ebook, self published, or non-published) you can still sell it through the bookstore. However, self-published works must be readily available in print.
In order to include your work without an ISBN number, please type the full work name without spaces in that field. (I.e. "Gone with the Wind" would be entered as gonewiththewind. Be sure to write that fake ISBN number down for future reference.