Petsmart stores have Milk Bone Essentials long lasting chews on sale for PetsPerks members (Sign up for FREE here) for $1.99 each. There is no limit and the sale is good until 5/2/10! Also I found these on sale at Target for $1.79 clearance so be on the look out for that as well. Please note: Prices may vary by region.
Here is how to get them for FREE: