All of the products seen on Shark Tank are in principle available for purchase. If the contestant did not receive a deal from one of the Sharks, then they may go out of business and stop selling their items. In this case, they cannot be bought through conventional means.
ABC's Shark Tank is a legitimate reality TV show, in that the Sharks invest their own money in businesses and products. Many of the items that become successful are available on e-commerce giants such as Amazon.com and eBay.com. Other successful products can be purchased directly from the websites of the entrepreneurs.