Merchant in the Trade building in Lower sells Bone Wands for 1GP (in unlimited stock) and the merchant in Upper sells it for 9GP (in unlimited stock). I reckon that's not intentional, so just letting you know.

It most likely is, since there is a tax on the uppers wares.

It doesn't have much to do with taxes, since the merchants in Lower have to pay equivalent amounts in protection money. It could be something else, however...

Which metafaction are you in?

Forum Metafactions: Lower, Old Dunwarren, New Dunwarren (Lower and Upper are added for everyone, automatically)

Server metafactions: New Dunwarren. I took the Underdark Portal on character creation.