I do have a membership at Costco and was thrilled when they started stocking organic products. They don't have a lot of things, but I have generally been happy with what I've gotten there. Here's a list of what comes to mind...
Frozen mixed veggies - 5 lb resealable bag, about $6.00 They are great, my 3 year old askses for them!
Pacific Natural Foods - 6 pack of quart stocks or soups, about $10 - way cheaper than $3.00 each at Central Market or Whole Foods! Just wish the packaging was recyclable.
Organic Pasta - great bargin if you eat a lot of it.
Some Newman's Own organic juices
They have their house brand of organic milk but it only is sold in 3 1-/2 cartons. We'd never be able to use it before it expired.
They also sell Silk Soymilk and some Horizon milk drinks in smaller lunch-boxsized packing.
They have a brand of organic pasta sauce that I tried, but didn't care for the flavor.
They have organic frozen blueberries for a very reasonable price - great for smoothies.
They have 5 lb resealable bags for organic baby carrots for $5.00 - half the price of buying the 1 lb bags.
Stoneyfield Farm Organic Yogurt - 12 6 oz cups for $8.00 6 blueberry, 6 strawberry.
Most of the other (limited) fresh organic produce comes in too large of quanties for me to buy. I will get the conventional avocados though. I have never gotten a bad one in many years of buying them. I have found that Super Target has good prices on Earthbound Farms Organic produce.
I know they have other stuff like peanut butter and jams.. I would also suggest you do a day pass and check out what they have. I don't know if Sam's has any greater selection, but I am not a fan of the Walmart Clan so Costco's selection is fine for me.
Are you aware of the list of top 12 fruits and vegetables to alway buy organic and the 12 fruits and vegetable that it's OK to get conventional? If you aren't, I'll send you that list or a link to it. Now I am going to check out the efarms link that one of the other moms sent to you. Good luck! N.