We get ours from a local Asian grocery store. Beef kidney and liver, pork liver, turkey gizards, heart, liver, back neck . . . all under 1.49 a pound. The don't have green tripe though. Lots of other end and pieces but the price per pound goes up.
But I was at costco yesterday and saw whole young chickens for 1.19/lb. Probably no organs but pretty cheap on the muscle and bone.