When I was a kid and money was tight my mom would add and sub black beans to any meal that used ground beef. Use the beans for half of the beef required. (Example, if the meal requires a pound of ground beef, do half a pound of beef and then an equivalent volume of beans) The beans take the seasoning of the beef well and make it significantly more filling. Works especially well for meals like tacos.

You can also sub ground turkey for ground beef. It’s much cheaper. It does require substantially more seasoning though because the turkey doesn’t take seasoning as readily as beef.