I pay $0.22/pound ($440/ton, I buy bulk). So a 50lbs bag for me would be $11. However, if someone wants more than $15 for a $50 bag I would say that they are ripping you off. Find something else, your hens will start eating what is in the feeder after they get hungry. After a week they won't want anything but their new food (and treats).
You paid $40 for 3 pounds of feed??? Were these organic tropical bird seed or something? I would go back and tell them they have made a mistake in pricing. You should never have had to pay that. I buy organic feed and just paid $23.50 for 50 pounds of organic, soy-free layer feed from Countryside Natural Products.