Buy lentils and other dried beans and use them to stretch out animal proteins.
Some examples: cook lentils in seasoned broth and add to ground meat for burgers, meatloaf, sloppy joes etc.
Experiment with recipes using beans, and practicing cooking with dried beans
https://www.cooksillustrated.com/articles/1745-can-baking-soda-make-beans-cook-faster
http://www.eatingwell.com/article/292167/the-weird-reason-you-should-be-adding-baking-soda-to-your-beans/
Cassoulet
Lentil Minestra Soup
Black beans and Rice
etc
https://health.clevelandclinic.org/do-i-need-to-worry-about-eating-complete-proteins/
adding lentils, quinoa or beans to your animal proteins can help your budget