Jeff Jarvis has a number of ideas. Among them:
Let me suggest a model, learning from both Amazon and eBay, where instant gratification costs more but patience pays off (which is also proven by Netflix.com). So:
* Charge the most for immediate delivery, which is enabled because you either stock some number of books in inventory or use more expensive print-on-demand. This is the equivalent of eBays buy it now! and of Amazons overnight shipping. Lets say that costs the reader $25.
* Charge less if the reader is willing to wait depending on demand one to two weeks. Over that time, you collect more orders for the book and can print it in larger batches (especially as print technology improves). I wait two weeks or more to get stuff from Amazon with free shipping. Lets say that costs the reader $20.
* Charge less again if the reader is willing to take the book as a PDF and read it in that mangled, inconvenient form or go to the expense of printing it themselves. Lets say that costs the reader $15.