Strictly coffee, or will there be baked goods as well? And southern or central NH? Dunkin franchises are quite expensive, and I believe they require you to open a few satellite locations, assuming you can actually buy a franchise. If you want to set up an independent shop, well the odds are probably against you. I don't drink coffee myself, but I know most places that sell coffee also do baked goods, ala dunkin and starbucks, as well as a bakery cafe along 111 near Benson Park in Hudson, but that's more a bakery that does coffee than the other way around. There's also a place called Five Star Espresso that is a drive through coffee stand on 3A in Hudson. Haven't seen many of those around, and that one is a TINY building with drive throughs on either side.
So the question is, do you want a just coffee place like five star, or a cafe that also has food?