GUATEMALA CITY — Some 450,000 pounds of organic coffee sit in a warehouse here, stacked neatly in 132-pound bags. It's some of the world's best coffee, but Gerardo De Leon can't sell it. "This is very high quality and it's organic. But ... the roasters don't want to pay extra these days," says the manager of FEDECOCAGUA, Guatemala's largest growers' cooperative, which represents 20,000 farmers. De Leon is asking $2 per pound for the unroasted coffee, about 50 cents more than the going price. But he says he'll soon have to sell it as conventionally grown coffee, which sells for...