Mainstream or Self-publishing

Last night I attended the opening night for my local art council's group show. I am participating in the show (a knitwear design, writing, and photography).
I was overwhelmed by the fount of knowledge that awaited me there.
You see I had mentioned to a few friends what had transpired with my manuscript submission. All where supportive. One friend suggested that I go the self-publishing route. I do plan to self-publish an ebook. However, self-publishing a children's book seems to me to be too expensive. She pointed out the advantages:
I would be able to retain artistic control on the book
I wouldn't have to share the profits with a publisher
I also would not have to tie myself to a publisher who may drop my book like a hot potato.
Our conversation was over heard by a book-seller. She pointed out that book-sellers shy away from self-publishers because:
-book-sellers prefer not to deal on a one-on-one basis with a large group of individual self-publishers. Work with a publishing house is much easier for them.
-self-published books tend to look amateurish.
So I am still on the lookout for a publisher for my children's book. However, I still intend to self-publish my ebook. The roadblock I have come to with my ebook is acquiring a ISBN number. "Where do you acquire an ISBN number?" You would think that all it would take to answer this question is a simple google or yahoo search. Unfortunately, this is not the case. I have tried repeatedly - to no avail. I have found tons of information. Yet, no answer to my simple question. So if any of you can help please email: leanne@oknitting.com You may prevent me from going preeminently bald. : )