-forget buying fresh produce during the winter months. yellowing broccoli for $5? No thanks.
-in the summer, go to your local farmer's markets to get produce. good quality, generally cheaper than the grocer
-depending on what coast you live on, there's a few farmers around who will sell you wholesale meat (Oliver's Farm comes to mind in St. John's, there's also a pig guy out west who travels around and delivers his pork)
-when you see sales on at Sobeys or Dominion for meat (every few months Country Ribbon will have chicken breasts nice and cheap, like $2/lb, or ground beef for $2-3/lb) buy as much as your freezer will hold.
-buy whatever meat is on sale that week. you might have to deal with eating pork for two weeks, then eating chicken for two weeks, etc.
-if you knows anyone out ATB that fishes, hit em up during food fishery and stock pile your freezer full of cod
-same with moose. go in with some buddies or your neighbour's nan for a license
-grow your own root veg. this might be difficult if you're in town with a lawn the size of a postage stamp, but you can grow potatoes in a barrell: 4 Simple Steps to Grow a Hundred Pounds of Potatoes in a Barrel | greenUPGRADER (disclaimer: i have not tried this)
-if you're drinking lots of milk, look round your local convenience store. milk really spiked in prices in the grocery stores, but I get 4L every week at Marie's for $7, not much more than cost.
Basically, just make sure you got a big freezer and then stockpile anytime butter/bacon/ground beef/chicken goes on sale, plus take advantage of the moose and rec cod season. Good luck!
Random fact: did you know that if the ferries broke down and we were stranded, the entire island would only have enough food for like, 3 days? Scary stuff.