I'm an enchanter as well as mage.  When crusader was still big, I had no problem getting a very large tip from people when I preformed it for them even when they had the mats.  Why should I get a 7g tip for clicking a button?  I paid 250g for the enchant itself and around 100 for the rod to use the enchant.  Thus, I get money for clicking a button; I had earned it.  If people are charging 200+ gold for a simple water spell and I buy it, I have earned yet another right to gain a tip for clicking a button.