Eh, not sure if you considered, Des Abats, beef heart, it is awesome, very good for you, it is a little leaner than other beef but it is as good as steak imo. Offal tends to be the cheapest meat in areas it isnt popular, but you may need to go to a meat slaughterhouse to get it if you don't have any good butchers.
I love heart, heart from pretty much any animal is a great meat. It tends to be with lungs, pancreas, liver, kidneys et.. the cheapest meats. Heart is just awesome.