Meritline offers two Canon-Compatible PGI-225 / CLI-226 Inkjet Cartridge 5-Packs (pictured) for $19.95. (Choose the "2 Sets (10 Cartridges)" option.) Coupon code "MLCA03UN" cuts it to $8.95. With free shipping, that's the lowest total price we could find by $3 outside of the mentions below, although we saw this quantity for $2 less last week (since expired). These cartridges fit several types of Canon PIXMA printers; see the "Compatible Printers" list on the product page for details.

Of note, DuraECO via Amazon and TonerDeal via Amazon have a similar 10-pack for $9.07 or $9.25 total, respectively.