According to the prices for magic items suggested in Treasure Companion, alchemists' incomes really start to lift off from the basic population at level 6 (they get to sell their level-appropriate works at twice the production cost at that point, and this also increases with higher levels). While an "average farmer" is supposed to earn a mere 4 copper pieces per day, a level 6+ alchemist earns hundreds, a level 11+ even thousands, a level 21+ even tens of thousands of copper pieces per day - on average.
Of course, not all magic users will be that wealthy, not even all alchemists. Alchemists of Channeling will be integrated into some kind of religious organization that likely siphons off much of their revenue, for instance. Nevertheless, the intention between this price structure for magical items seems clear: Level 6 is where the social "elite" begins.