Retail prices are a guide but you may be able to do better. For instance Publix often has "buy one get one free" sales, including things like tinned vegetables or chicken. Progresso canned soups, often $2.59 each, are sometimes on sale
for a dollar, or at least "two for one". Obviously you can't depend on that when you need to stock up, but you CAN tell the store manager that you are provisioning a boat, making a very large purchase
, and ask if he can make you "any accomodation" or suggest if anything on your list is about to be put on sale
At least with the Publix chain, they're very
accomodating. Groceries in the US can be very competitive and almost always will extend some extra discount or courtesy to you if you simply ask for it. Especially when you are making a substantial purchase
Another option is to use a Costco, Sam's Club, or BJ's membership
discount. The membership
may cost $40+ for a year (which might be one use for you) but if you ask around, often someone is a member
and will take you in. While the selection is more limited than a supermarket, some of the prices on tinned goods (i.e. 8-pack of soup, or 3 jars of fruit, or 8 cans of green beans, sold as units) are quite competitive and often beat supermarket sale prices.
They usually don't publish prices--but it may be worth your while to check them out before you actually start loading up.