I carry a plastic coffee cone and paper filters. Many bigger grocery stores sell coffee in bulk, so you can buy & carry only as much as you'll need until the next resupply location. That said, I often buy a whole pound, that's how important coffee is to me.
Starbucks Via is really quite good as instant coffee goes. Expensive, but very light, and no equipment needed. I discovered this recently, haven't decided yet if I can rely on it for a longer tour, it's not in that many stores.