Looking for ideas with very few ingredients and nothing fancy.
Pasta Sauce
Tuna
Cheese
Mix into a casserole bowl and put into a hot oven for 10 minutes.
They make great meals out of cheap cuts of meat so you can buy cuts like gravy or chuck steak or lamb shanks or chicken thigh instead of breast.
google for recipes and you will find plenty of tasty recipes that can be made quite cheaply. Most slow cookers come with a recipe book as well. Also McCormicks have a range of slow cooker recipe bases now that you can find on the supermarket shelf with the rest of the recipe bases, most only have 5 or 6 ingredients that can be purchased cheaply.
good old pasta and pesto always wins. Beans on toat, omellete, potato pie etc can be brightened with a tin of cheep tomatoes or a sprinkling of cheese.
We always have a dessert as this always feels like a treat but can be cheap. I make up a jelly and find the cheapes fruit [tinned or fresh] that I can. put some fruit in 4 smallish glasses and top with jelly. it looks lovely. buy some really cheap icecream or sponge cakes and cover with hot chocolate custard or save a little of the jelly back, chop it and sprinkle on icecream.
Cabbage, potatoes, onions and pork ribs
http://www.pueblo.gsa.gov/cic_text/food/rec-thrifty/recipes.htm