I got constructive criticism from a friend who questioned the smallest levels of donations ($1 and $10). If you are interested in the book, why would you want to give <$17?
My idea with a lesser amount than the book price, is that if you want to support this project, but can't afford the book at this moment, you could do a symbolic gesture. For your information: I wanted to set the book donation to $17.73 as a symbolic number (the year of the Boston Tea Party, 1773).
I wouldn't mind getting $1 from 2000 supporters / $10 from 200 friends, as this sum would cover a big part of this project (illustrations, editing service, publishing fees, marketing activities, etc.).
Another thing that I have to cover is the shipping and handling of the book and the original artwork reward. I have set the amount of $25 for shipping & handling. It could be the case that I have to adjust this dollar amount, depending on the shipping destination of the supporter.
If you have suggestions for new perks, please let me know!
I am planning to send the supporters at the $17 level, personal updates with book material on a regular basis (every fortnight).