When first getting started with eCommerce, it’s quite common to turn to a hosted shopping cart provider like Shoppify or Instant e-store. You might also try using PayPal and/or Google Checkout to accept payments for products or sercices. The main advantage of these options is that most of the setup is done for you, so it’s quick and easy to get started.
Eventually, however, many businesses will want to have a standalone shopping cart on their own domain. This can be more seemlessly integrated with the rest of your website, and the cost per transaction should be less than with a hosted solution. You also have a great deal more control over your storefront.