It's enough but he's double charging you several times.
80k/point, ok fair. But then he's also charging you for the XP you gain while getting those points.
8M for favor and 60gp/xp to 34 farming but you also gain farm XP while getting the favor. >_>
How do you figure it doesn't give an advantage? Cannon has insane DPS.
He buys cannon + balls you buy the rest of the stuff you need, gear, food, pots etc.