Shopping Carts are a necessary component of having a website and a blog. Without some for of shopping cart, you won’t be able to sell products on your site. OneStopShoppingCar.com is one of the most popular but one of the most complicated to set up.
PayPal is the easiest system to use and probably one of the most often used. All you need is a checking account to set it up. The challenge with PayPal is you can not process credit cards you’ve collected while out speaking only when someone goes to your site to purchase your products.
Google Checkout is another shopping cart that allows you to avoid using a merchant account service. It is easy to set up and you can take credit cards when you’re out speaking and process them online when you get back to your office.
What you might want to do is ask other authors what they use and why they use them. You’ll get a sampling of what others opinions are of the various resources.