Liver contains plenty of protein, iron, and B vitamins. It's also one of the best animal-based sources of vitamin A. One serving of beef liver, for example, provides more than 100% of your daily vitamin A requirement. Getting enough vitamin A has been linked to a lower risk of conditions like cataracts and breast cancer.
 
Liver is also a good source of:
Vitamin C
Potassium
Phosphorus
Copper
 
Sold in 1 lb packs at $15/ lb