Ok here are steps follow carefully.
1)clear all cookies related to amazon.com
2)click on link i provided and you see option for amazon prime under add to cart button.
3) add book in cart and start yr 3months free trial.
Note: you dont have buy book.
4)Under your firstname.lastname@example.org change yr option for prime membership to "not upgrade automatically"
Note: you don't have to buy book.