As far as cheap quick and easy it’s hard to beat Midwestern style “salads”. Egg salad is something I eat fairly often. Mix hard boiled eggs, mayo or miracle whip (I use light), and sweet pickle relish in whatever proportions you prefer. I generally add some frozen peas and top mine with Tajin powder but you can add veggies, nuts, seeds, cheese, seasonings or sauces… whatever you want to customize it. To make a different kind of “salad” replace the eggs with ground, chopped, or shredded meat (home cooked, deli, or canned) of whatever type you prefer or a can of beans with the liquid drained. It can be made into sandwiches, wrapped in a tortilla, used as a dip, served over rice, noodles, cooked or fresh veggies, it can be eaten cold or hot, if you add a lot of veggies, pasta, or rice and some liquid it can be baked off as a casserole maybe topped with cheese. The meat/eggs/beans should be cooked before they go in so all you have to do is dump it in a bowl and mix it up.
For a dessert “salad” there is cottage cheese salad. Mix a tub of cottage cheese, a can of fruit (pineapple is the norm but I use oranges because I don’t like pineapple and it’s suppose to be drained but I don’t), and a small package of flavored gelatin (sugar free store brand works fine) in a large bowl then fold in a tub of whipped cream. Sometimes I add some cherries and/or walnuts. Any fruits, nuts, or seeds can be added. It has to be refrigerated for a couple hours so the gelatin can set up.