You can do much better with Print On Demand.
Although my books are not tech (they are religious), the same principles apply.
After you produce the PDF for text and cover, your work can be done (except for marketing). I use Lightning Source for production and have all my titles listed with Amazon and every other bookseller. Lightning Source's fees are very reasonable, and Amazon takes whatever percent you allow. They handle shipping, credit cards, etc.
My total out of pocket for book production was very low (~130/book) and I can purchase bulk orders cheaper than I sell to Amazon.
You really don't need to spend a lot of money nor do you have to store any books if you do not want to. As both the author and publisher, my return is much higher per sale than through dealing with a publisher.
However, a publisher will help you with editing and marketing (although you pay dearly for both of those).
I'm still in the process of building up my site, but drop by http://godsvaluesystem.com/
I also have a friend that works on an offset press and he confirms that the book quality from Lightning Source is excellent.