I'm not sure if this idea has been thrown out there yet, but if possible, a Cove ABer would probably be the most profitable. Then again, I'm not quite sure exactly as to how it would work with the dubloons and everything...since I've never actually bought anything from there. Oh well, it's just an idea
This would not really work seeing as if you refresh at the cove too many times, you get banned from the cove for x amount of time. In theory it would work but in reality, nah.
Hm... Like alone1 said, you get restock banned from there extremely quick. It'd be almost impossible to actually snipe something from there.