I am currently leaning toward self-publishing my book via Amazon services. However, before I do, I am considering the pros and cons of searching for an agent or publisher. Please note that everything I am saying here is particular to my own situation, and I am not trying to make a general standpoint about the state of traditional or self publishing.
In my case, my book is complete and professionally edited, I am not that bothered about making money, and I just want my book to have the widest audience possible. That being the case, it seems publishers only have three advantages over self publishing. Access to distribution in book stores, marketing assistance, and the credibility of being associated with a publisher.
The issue of credibility is too multifaceted to cover in this question, so I'll just put that aside. More concretely, if I am willing to give up on access to book stores since distribution by online services seems sufficient for me, then all I really want is help in getting the word out about my book.
Are there people or companies who will help only with promotion in concert with online self-publishing? I might be using the wrong search terms on Google, but it seems all my queries end up at the same place, traditional publishing companies.
If book promotion specialists exist, do any of them work for percentages of sales? I would be hesitant to hand over cash in lump sums for the promise of promotion, as it seems their financial motivation would be in pulling in authors and not in pushing books.