Walmart doesn't offer BOGO type deals. But their house brand is cheap enough that even if another store is offering one Walmart brand is, often, still less money. But even then if you own the equipment and have the time it's still less money to do it yourself from dry.

Jams, jellys and soups.

I have general rules. If fruit is available for less than $1 a pound. If berries are less than $1.50 a pound. If boneless meat is less than $3 a pound. If bone in meat is less than $4 a pound.

If any of those criteria hit then it's time to think about canning. At those prices points you can probably can something for less than you can buy it. It helps to remember "a pint is a pound". Most non-dry items are pretty close to a pound per pint. Meat, tomatoes, blackberriesx whatever. Each pound of food can probably fit in a pint jar if canned. How much would you pay for a can of Spam? Probably about $5. How much is a pound of ham? If it's $3 or less then it's going to be cheaper to can your own than buy it. Need blackberry preserves for your PB&J? If Blackberries are less than $1.50 then it's going to be less money to make your own then buy the cheapest jar of blackberry preserves.

These numbers need constant adjustments for inflation.