I just wanted to add:
there is no best weapon for barb
all weapons are different so is their prices.
Axes : very constant dmg , they're not the cheapest weapon though
Swords: very UNconstant dmg ( highest critics and very low dmg ). You can use them on the 3 first classes ( feeder , samy, pala ) so they're expensive
Clubs: dmg between sword and axe. You can't use it if you pass Samurai so they're the cheapest.