Willimantic Food Co-op (CT)
They do still add 10% to your bill if you aren't a member. I'm not sure what your standards are, but they have a decent array of fruit and veggies, lots of locally produced items, like cheese, milk, honey etc, but not limited to local stuff. You can get an individual membership (no family memberships available right now) for the afforementioned $120, but you can opt to pay $20 a year until it's paid off, and if you want out, you get your money back.
Fiddleheads co-op is supposed to be opening in New London soon. We'll see.
I'm not sure if Willi Food still has different prices for members and non-members or not, I have a feeling they may have done away with that system (as many coops have) when they moved to their new space. I haven't been since they moved, but they're wonderful people running what seemed to be a very nice coop. Certainly go and check it out.
One side note: very, very few food coops are members only. Park Slope in BK, Mariposa and Philly, and I can't think of anothe rin the northeast.
It is a decent place - although I hear they have a new location now, and I havent been there. Anyone can shop there from my recollection - you just pay a 10% upcharge or something like that. If you want to be a member, you throw $120 into the pot or something...and you could always withdraw from the Coop and get your money back.