Wow, you and I are in the same boat. LOL Picky eaters and low budget but want to stay healthy! We eat a lot of chicken and I look for it to go on sale. I will mix chicken, a can of low salt black beans, a can or corn and jar of salsa and then we put that in whole wheat tortilla boats and top as we like with lettuce, tomato, and cheese. Then sometimes I use the left overs (as it mixes into quite a bit) and put it in scooped out and boiled peppers (like stuffed peppers) and pour tomato sauce over and bake. Tasty!
Stir fry is a good one too because everyone picks out what they don't like. lol You can make a sauce out of orange juice and soy sauce and thicken it with corn starch.
If you make cheap and a typical favorite spaghetti, put a few covert veg's in the sauce. :>)