A cheap cut of beef steak is "chuck". You can get 2-3 good sized ones for about the price of a T-Bone. Not too tough either.
Try roasted soybeans. They are cheap and very "tasty". I prefer snaking on them instead of peanuts.
As far as chicken and tuna go, check the online fliers for all your local grocers. They are 'drawing cards' and are often sold very cheap (or BOGO). Stock up on that kinda stuff. Same w/ frozen veggies. For fresh veggies - most produce departments keep a "marked down" selection at the back of the department. Great deals there! I bought 2 lbs. of bananas for 51 cents the other day. Good condition.
You can buy milk at your convenience store a lot cheaper than the grocer. I get mine for $2.00 a gallon at the Expressmart up the road. It's about $4.00 at the grocers.
Also, check for "double", and "triple" coupon days while reading those fliers. Most sites have their own printable coupons too.