Meritline offers this Canon BCI-6-Compatible Inkjet Cartridge 3-Pack (18 cartridges total), bundled with 20 sheets of photo paper for $18.95. (It's the first option under "Buy More Save More".) Coupon code "MLCS07BN" cuts it to $13.95. With free shipping, that's the lowest total price we could find for the ink alone in this quantity by $9, although we saw it for a buck cheaper last month. It's compatible with Canon i9950, i9900, and i900D printers, among others.
TonerDeal via Amazon still offers a Canon-Compatible PGI-225 / CLI-226 Inkjet Cartridge 10-Pack for $2.76 plus $4.99 for shipping. Outside the price below, that's the lowest total price we could find by $4, although we saw this quantity for $1 less in November. These cartridges fit several types of Canon PIXMA printers.
A close price: Meritline has a similar 10-pack (two 5-packs) for $14.95 via coupon code "MLCR26TN", $7.95 after, with free shipping.
Meritline offers two Brother LC75-Compatible Inkjet Cartridge 4-Packs (8 cartridges total) for $8.95. (Select "2 Sets" under "Buy More Save More".) Coupon code "MLCR19GN" cuts the price to $6.95. With free shipping, that's $2 under the lowest total price we could find for a similar cartridge set elsewhere. It includes one of each: black, cyan, magenta, and yellow.
Meritline offers the G&G PGI-250XL / CLI-251XL Canon-Compatible Inkjet Cartridge 5-Pack with Chip for $20.95. Coupon code "MLCR17EN" cuts them to $14.95. With free shipping, that's $2 under our mention from last month and the lowest total price we've seen. (It's also a current price low by $15.) These cartridges fit several types of Canon inkjet printers; use the compatibility chart on the product page to check specific models.