The term Kona Coffee Company is used for producers of Kona coffee. One company can have different plantations, this ranges from small producers with just one plantation to larger ones with dozens.
Most classic Kona Coffee Companies offer the popular pure 100% Kona coffee and no cheap mixtures with cheaper coffees that are called blends. There is a huge variety of websites where these companies offer their coffee, some even publish their offers and Amazon while others rely on direct sales via their own website.
One of the most popular ones offering great quality is Koa Coffee.