I don't think there needs to be economic balance between the disciplines. Even in real life someone who runs a successful business is going to earn more than someone who mines coal for a living or joins the army.
I still think the better solution is to give battlers their own content to make money from that crafters can't get involved in. (Selling loot that from NMs and dungeons). Crafters will always be involved in the gatherer's content because without a crafter anything that can be gathered is trash.