Adorama offers the HP 21/22 Ink Combo 2-Pack, model no. C9509FN, for $25.79. Add two to your cart and they come to $47.90. With free shipping, that’s $23.95 each and the lowest total price we could find for this quantity by $11. Each pack includes a black cartridge and a tri-color cartridge of cyan, magenta, and yellow.
Update: The quantity has been corrected.