Wow, GrantMeAName, your prices strike me as very high for grocery stores. Many of my grocery stores are less than your Costco prices by a good bit. I think that not only are there differences between countries, but between regions in the US. (I'm deep South.)
-Shredded cheese is like $2.35 a pound compared to about twice that at the grocery store.
-Gorgonzola and feta are like $4/lb compared to twice that or more at the grocery store.
-Sliced aged (really good) cheddar cheese for sandwiches is $3.50 instead of $7-8/lb at the grocery store.
-Unsalted butter is like $9 for four pounds, compared to $4 a pound at the grocery store.
-Eggs are $2.89 for 36, just under a dollar a dozen, instead of $1.49 a dozen at the grocery store. We eat enough eggs that we get 36 every time we go.
-I buy shredded cheese at the grocery or Walmart when it goes on sale for $1.99 a pound (not unusual).
-Don't do the specialty cheeses you mention, so I can't compare there.
-Butter here is just over $2 a pound (I haven't bought it in a while because I'm not out, but I know I saw $2.29 about a month ago -- butter keeps well in the freezer, by the way).
-Eggs, though, you've got me there. It's usually $1.68 for a dozen large here.
-Yogurt is $3.99 for 2 quarts instead of $5.50 for the same quantity at the grocery store.
-Hummus is $5 for a quart instead of $5 for 6 ounces.
-Frozen berries are unbelievably cheap -- mixed (blue,black, rasp)berries are like $3/lb, and strawberries are a little less than that. It's the only way we eat berries for nine months of the year, and it's probably like a third the reason I'm such a Costco disciple.
-Yogurt is $1.68-$1.98 for 32oz (= 2 quarts)
-Hummus? Well, chickpeas are approaching $2 a pound, which is sickening, but a pound of dry chickpeas makes over a pound of hummus, and mine is better than the store version. Add the cost of a few tablespoons of olive oil and whatever flavoring, usually garlic. If I did buy it, though, the 6 ounce tubs are $2.99 here.
-Frozen berries are free here, since I pick them and freeze enough for the year, so I can't comment on the comparison.
Meat:
-Good-quality roast beef is $5.50/lb instead of $9/lb.
-Ground turkey is $2.69 a pound instead of $4.79 at the grocery store. You have to buy six pounds at a time, but it comes in self-sealed 1.5lb containers that freeze well. It's actually cheaper than ground beef, so we use it almost exclusively for all our ground-to-a-paste-meat needs.
-Boneless skinless chicken breasts are $2.29 a pound, which is less than however much they cost at the grocery store (I couldn't tell you). The 10lb bag takes up a lot of our freezer when it's new, though.
-Bone-in chicken pieces in small (8oz) packets are either $.99/lb (wings and drums) or $1.99/lb (thighs).
-Frozen boneless, skinless, self-sealed salmon and trout filets are $5.69/lb for three pounds, compared to $8 or more at the grocery store for a lower quality product.
-Whole primal cuts of steak are usually about 2/3s the individual price. We often buy a whole one, slice it into steaks, and freeze it to eat over a few months.
-Pork tenderloins, pork chops, and pork or beef ribs are a good deal cheaper than at the grocery store. In the summer, we often get the ribs, because they're like $2.29 a lb most of the time.
-I sucked it up and paid $5 a pound for a roast the other week, but I generally don't do that because of the cost; we just don't eat it much. Venison is healthier, anyway, right?
-I switched to TVP years ago, so I don't buy ground beef or turkey and don't know current prices.
- I buy 5-10lb bags of boneless, skinless chicken breasts, too, for $1.99-$2.29 at the grocery.
- for the bone-in wings, drums, and thighs, I buy 10 lb bags of chicken leg quarters when they go on sale for 68 cents a pound (my new "buy" price, up from 48 cents two years ago.
- We don't do the salmon or big cuts usually, so I don't know prices.
- Pork chops and roasts run between $1.68 - 2.29 a pound here.
So, region matters, I think. My go-to grocery stores are Sav-a-Lot and Walmart; I don't know prices at the full-price chains. I wonder if Costco in this area is cheaper than in your area, too? I won't be making the comparison any time soon, though; it's 90 miles to the nearest Costco.