Where the money for your calculus text goes. There really isn't any reason why an free open source text can't be used instead for a course like calculus .. http://castingoutnines.wordpress.com/2009/04/06/where-the-money-for-your-calculus-book-goes/
I only use open source textbooks.
Open source (or no textbook at all, for those of us in fields where that is possible) is the answer, I think. That makes me a bit sad, because writing a textbook (like teaching) is serious intellectual work, but doesn't seem to get much credit toward promotion/tenure (assuming one is eligible for same, which 70% of all professors, and, presumably, an even higher percentage of teaching-oriented professors, aren't) and it would be nice if professors could at least earn a bit of money for such labors. Heck, I was thinking a few days ago about whether I could turn a series of assignments on which I've worked quite hard into a textbook. But the textbook publishers are so insistent on making an exorbitant profit, that I'm quite sure that not only would my students be gouged, but I probably wouldn't make much either. There are some small publishers that, at least in my opinion, give fairly good value for the money, and I use one of their books. But for the most part I just write my own materials and have students read things they retrieve from library databases. In my field, that works.
You could always self publish it if you are mostly wanting it for your own classes. I've heard good things about the book quality of lulu.com