Search your printer model, select the Moustache-branded result if one exists, and choose the largest multi-pack size your printer will actually use within a year.
123ink.ca's own house brand, Moustache, is priced below the equivalent name-brand cartridge and shows up across Clearance, Hot Deals, and the regular catalog. Switching your printer's ink or toner order to the Moustache equivalent is one of the few savings moves that works on every order, not just during a sale window.
Cartridges and toner also come in multi-packs from 2-packs up to 10-packs, and the per-unit price drops as the pack size grows. If your printer burns through the same cartridge every few months, buying a 6-pack or 10-pack once locks in the lower per-unit rate instead of paying full single-cartridge price on repeat orders.