Adorama offers the Canon Pro Platinum 13×19″ Super High Gloss Inkjet Photo Paper 10-Pack, model no. 2768B018, for $14.95. Add three to your cart and they fall to $32.85 ($10.95/pack). With free shipping, that’s the lowest total price we could find for this quantity by $20.
Note that you can purchase three or more of these packs for $10.95 each.