Many of the cacti that produce dragonfruit are surprisingly easy to grow and bloom and can even make pretty decent houseplants for those who live in areas without a tropical climate. I don't know about your specific situation or the finer details of the one amazing dragonfruit you had, but like so many things, home grown and fresh harvested dragonfruit usually tastes better than store bought. Just a thought, but if you haven't already considered it, maybe give it a try and grow your own. It'll probably be a few years (or more), but better than waiting a lifetime.