I think the payment model could be tweaked. If micropayments were embedded in the document, it could be possible to have the first 5 chapters free then ask for a micropayment per remaining chapter. A minimum of 10 cents per chapter and at the end of the book prompt for more if they liked it.
For people to pay for an item they need to believe the item has some distinct value. A PDF which has no physical body and barely any cost to create doesn't have the same perceived worth compared to a paper book where the reader knows cost has gone into the actual production of additional copies. With e-books the cost that has gone into 'printing' additional copies is perhaps 0.0001 cents per copy. If the reader believes there is little cost to the author they may be less inclined to pay for it.
So the donation scheme may not work without additional incentive. I would suggest:
- First half of the book then a minimum donation of $1 for the rest of the book. If they get that far they are enjoying it and most people will pay (who leaves a book half read over $1).
- The method of payment MUST BE fast, simple and easy. You lose consumers if they have to create a paypal account or trudge to a specific website (putting down their reader to do so). Ideally the micropayment method needs to be integrated into the reading device with existing payment methods.
- Offer half of the money to charity. Make the minimum payment $2 but $1 of that goes to cancer research of some kind of charity. People gain the added benefit of feeling good about themselves when they make a purchase, you feel good about donating hundreds/thousands to charity and you get more sales.
- Also there need to be limited edition real world collectors edition versions of the items. Nine Inch Nails who gave away their last album for donation made millions of dollars off the limited edition versions, which as I recall were vinyl and some nice artwork (and may have been signed by the singer). See
http://theslip.nin.com/
They sold out of that initial pressing I believe, netting the band some 1 million dollars or so. Consumers who become fans of your work will pay additional amounts for physical versions of media. If they LOVE your work, their $1 ebook purchase can turn into a $40 signed hardcover purchase, you need to upsell these people.
Independent E-book authors have the advantage of being able to see the music model where people have tried and failed at certain things.