You can sell on ebay and amazone both as private seller or business seller. Its important to research your product carefully before starting
to sell it online. It will help leaving good impression on potential customers. Selling products on internet is almost free, if you have some web development knowledge, by using Paypal as your payment processor. Paypal's processing charges are competitive and you don't need to have SSL ( Secure Sockets Layer is cryptographic protocol for security on internet ).