This deal has ended.
Through 8/9 OnSale.com offers a $20 Voucher to PetCareRx.com for $1.99! As an example, PetCareRx has Joint Health Plus for Dogs for $19.99, so you'll get a 3 month supply for $2 by buying this voucher. There is a limit of 1 per person and the value doesn't expire until 2/5/12. Shipping adds $5.99 but is free on orders of $35. Sales tax is charged in most states.