Asheville has about a 3-4 month mango window, where the best of very sweet Mexican mangoes make it into most supermarkets and farmers markets at reasonable prices.
I will let my husband Allen share his perspective on mangoes:
This is my favorite way to eat very sweet mangoes. Kade's a machine when she cuts them. And Thais know how to cut their mangoes, a fruit that's available year round in the "Land of Smiles." When hungry, I can eat four whole mangoes a day. The first really sweet mango I ever tried was in New Delhi. I had a lassi, in fact, and it was incredible. I remember returning to Headland after my stint in Central Asia and that travel experience in India, and I discovered from Uncle Watty that he loved mangoes. The ones he would buy, because really good fresh ones weren't available, were actually chilled mangoes in a jar. He loved them! Years later, I remember visiting him on my returns home from Thailand, and feeling kind of sorry for him because he would not ever be able to eat a super fresh, super sweet mango that you might just take for granted if you were Thai. Nowadays, golden Mexican mangoes are making it into our markets, and they are just as sweet as Thai ones. All I can say is stay away from the reddish-green variety of mangoes in the supermarket, and only buy the golden or champagne mangoes - that is, if you want sweet ones! When not eating mangoes freshly cut, we sometimes dehydrate them using an Excalibur. Other times, we make shakes using the Vitamix 5200.
And when the mango gets really nice and dry, box it in plastic. Stores forever.