AuraSeer said:SNIP
It's true that a hypothetical create food item with no use limit could offer a solution. It would theoretically cost 27k, and activating it for seven hours nonstop could generate food for the whole city. But that's only if the DM allows arbitrary magic items, and (unwisely) goes strictly by the price guidelines in the DMG. I don't know anybody who actually plays that way.
Even if you do have "at will" items like that distribution of the food can be troublesome and will drain resources from the fight
As far as the guidelines as written I use them I to an extent --
in the High Magic Era version of my game a device like that called a Crucible and is standard in every city. There is usually one, a ore powerfull version that takes only 1 round to activate per 5 or 10K population
I guess it all really on how much magic is standard in your campaign


