Walmart offers the Wagner's Four Season Wild Bird Food 20-lb. Bag for $8.45. (Home Depot charges the same.) Choose in-store pickup to avoid the $5.99 shipping fee. That's the lowest price we could find by $9. It purports to attract a range of wild birds, including cardinals, doves, and woodpeckers.

Update: The price has increased at Walmart; however, Home Depot still offers it for $8.48 with in-store pickup.