If you don't have Dan Poynter's book "The Self Publisher's Manual" you should check it out.
The cost of self publishing a hundred thousand 500 page trade paperbacks is about $3 a book. The cost for only 1,000 is not that much more, about $5. Modern technology allows very efficient short runs. So as far as creating the hard copy work, you don't need a "publisher" any more, only a printer, and there are 100s. Their offset ink printing and binding work is indistinguishable from the largest "publishing houses" in NY.
So that leaves promotion and distribution. Promotion is more do-able today than ever because of the internet. Ditto distribution. Books by unknown authors sitting on shelves at B&N have a 90% chance of being returned, and then you are finished with few second chances.
Just some random thoughts, I have to run out the door, more later.