It's real simple: Give new members an Amazon gift card to purchase the book. You buy the gift card, then send the code. Or, buy a gift card to their local bookstore so they can walk in and buy a physical copy, or they can use the funds to place an online order and have the book shipped through the store.

The best way to get a book club off the ground is to make sure everyone has the book in hand before the discussion starts. "First book on us" is a great way to build momentum, and it lets people know that you're serious about the project.