I have membership of a couple of different cash and carries. Still get big sacks of potatoes and other veg cheap. Potatoes and onions keep, but a sack of cabbages is only worth buying if you are sharing with others.
Tuna has went up a lot, but most all canned meat / fish has. Best thing you can do is have a chest freezer and a vacuum packer. Get good deals on turkey, goose and gammon just after Christmas. Joint the birds up and vac pack it. Once that is done, freeze and stuff keeps pretty much for ever.
You can get different deals at different times of the year on meat. Been good for beef this year so far, regularly getting topside at £5/kilo for British meat, whole pork bellies for £3 / kilo British meat.
My local Costco have a load of American pork in the last couple of months but I have not bought any, sure in America they feed pigs on twinkies and hormones
If you shop around and can buy and store bulk, you can still get quality and value.