EZBuyButton Buy Book Widget for Authors plugin allows you to embed the EZBuyButton on Posts, Pages, and on the Sidebar. EZBuyButton is a "buy now
How can I hide/show the EZBuyButton Embed Code Custom Field on Posts and Pages? When you are in the edit or add new mode of a Post or Page, click on Screen Options, and you can check or uncheck EZBuyButton Embed Code to either show or hide the custom field from appearing.
How can I set whether the EZBuyButton appears on the bottom or top of Posts or Pages when it is published? Go to Settings -> EZBuyButton Settings page. Here you will have the option to switch between bottom or top display of your EZBuyButton.
If you have questions or need more information please go to http://www.ezbuybutton.com/wordpress-plugin