If you're just starting to sell online,and you're selling a single class, workshop, ebook or product, setting up a whole online shopping cart and merchant account is not going to make a lot of financial sense. The set-up, start-up and ramp-up costs associated with most carts will be too high to make setting up your products online worthwhile.
Instead, set up your single-product cart through Paypal's business solutions. Sure, their transaction cost is a bit higher than the average merchant account. But their accounts don't have a sign-up fee, and setting up your products with Paypal is (relatively) simple – especially compared with the learning curve on some of the carts out there. Their site makes it easy to generate product order buttons that you (or your designer) can then copy and paste on to your website.
Of course, you'll also have to set up a Products page on your website, and it's a good idea to run a promotional campaign (send newsletters, run a teleclass, etc.) around your new product's launch. And don't forget the customized thank-you page that people will see after the transaction – telling them how to download their product, dial in for their teleclass, or where the workshop is and what to bring.