There seem good advantages in POD (Print On Demand) publishing. I discuss some issues in POD   at http://pages.bangor.ac.uk/~mas010/orderbook.html


I have found createspace.com a good publisher for my book "Topology and Groupoids"; they are an amazon.com company, and this has the implication that the royalty rates are good (black and white, 6" x 9", 200 pages,   price  20.00 dollars, gives $8.75 royalty). Non exclusive contract. 

You should consult the e-book "The Fine Print", written by a copyright lawyer, Mark Levine.  

All the publicity, and sending out review and complimentary copies,  has to be done by you - this is a typical downside to any self publishing. 


Later: Another disavantage is that many libraries and insitutes buy anything issued by a major publisher, but have to be persuaded to buy a book which does not have the cachet of having satisfied the refereeing process of a major publisher. The advantage of this  amazon.com company is that the royalty is direct on the published price for amazon sales.