One of the keys to keeping coffee long term is in the roasting. Dark roasts bring the oils to the surface, thats what makes the beans look shiny or even wet. The oil
turns rancid real quick when brought to the surface. For both taste and longevity a medium or Full City roast will give the beans a longer and healthier life. Besides, charcoal tastes like charcoal leave the burned coffee for Starbuck's fans.
Vacuum packing keeps air from the beans. Air means oxidation and breakdown/rotting of the beans. It also retains any volatile elements in the beans. Vacuum packed beans will last for a very long time, like years. Unfortunately, they won't have that fresh from the roaster robustness much past a year though still drinkable.
If you are a real coffee nut, you can buy green beans, vacuum seal them, and roast them as the need arises. With care, you can roast the beans in a good frying pan. One caution, you will end up with a blue fog
hanging around head
height that is very aromatic, though on the burned side, and takes quite a while to dissipate. If you're into mechanization, an air popcorn popper does a more uniform roast. We found green coffee in the Marquesas
and I'm sure you can get green coffee anywhere that coffee is grown.
Don't even think about getting Cherry coffee from the roadside. The time and pain involved taking the coffee from the picked cherry to the roasting stage is not hand labor efficient, btdt. If you pay yourself a nickel an hour for your labor, it will still be the most expensive coffee that you've ever drunk.
I'm a recovering coffee farmer drinking a bit of my own stash that I roasted with a popcorn popper this morning. Do it for the fun of it, now that I'm no longer farming seriously.