At Leanpub, our variable pricing model allows authors to set both a suggested price and a minimum price for their books and courses.
Purchasing options are presented to Leanpub customers at the top right of the book or course landing page, like this,:
As a reader, this allows you to choose how much you want to pay, by moving the pricing slider to the left or to the right, when you're making a purchase.
This encourages readers to pay what the author thinks the book is worth, at the suggested price, but it also lets people with different capacities to pay, choose a different price.
Many Leanpub readers actually choose to pay more than the minimum and even the suggested price, usually because they want to give extra support for the author.
To be clear, everyone gets the same book or package as anyone else, regardless of what you choose to pay!