Ah, this is a difficult one, isn't it? I think of the criteria as "fair value for money". If the pies are home-made, delicious, and the same price roughly that you'd pay for them elsewhere, fair enough. AA is using gas, hydro and water that we have to pay for; their contribution helps. If you enjoy music and the sanctuary has good acoustics, a nice sound system, and a beautiful old concert grand, why would you not enjoy an inexpensive concert? We tend to make coffee/tea "free" with a "free will offering jar" which usually covers most of the cost, of the cookies at least, lol. We also have stuff for sale, like lenten reflections and calendars, but they're usually offered 'at cost', or even a little below.
But then, when our building hosts a lecture series for an outside group, we actually charge $5 or something for coffee/tea/goodies, and when we cater a funeral from outside the congregation, there is a set donation in exchange for said catering. So there you're getting into a bit of profit that makes some people a little uncomfortable, myself included.