I think I put this post in the wrong place before so here it goes again :)
Where do you buy berries that are not in packaging? I can't find any around here that aren't in plastic. The farmers market in My town is closed for the season.
The simplest thing is, when available, to buy at a Farmer's Market and immediately give back the container. During the off season, since you can't "buy local", use berries you've previously frozen.
Something to plan for next summer, locate pick your own locations and determine how you're going to process (dehydrate fruit leather, make jam and can, freeze sauce, freeze whole berries...)
Right now it is one of the few things we still buy in plastic bags (I think they're more recycable than the clamshells).
Yeah, they are definitely hard to find. Definitely has been a frustration for us too.
There are no organic or sustainable berry options at our farmers market during the summer, but our local Whole Foods does carry some organic strawberries (local, a state over) for about a month that come unpackaged. I try to buy a bunch of them and freeze whole berries and make freezer jam so I get to have them a little longer.
Why do they have to be organic? Organic is just a marketing gimmick, I go out of my way not to buy organic. I buy berries from a few markets that have them in those cardboard looking containers, and I just put them in the compost bin.