Congrats on the book! I would set up a Square online store. There is a free option. You can direct customers there to buy.
Also when you set up your item in the Square dashboard you can enable a direct checkout link and send the link to customers for checkout and purchase.
To order a Square reader go to your dashboard and in the top right you will see your business name. Click on it and a drop-down menu will appear. Scroll down to the ORDER SQUARE HARDWARE option. You will see the different types of readers there.
