I use genuine Canon ink but I get it cheaply..
I've owned a Canon PIXMA (whatever that means.. I suspect it's a made-up word, like "Kodak").. ip90, which is a do-everything, extremely compact, feature-packed printer.. although it's half a dozen years old, it still works fine.. it'll print on plain paper, labels, and do stunning photo prints on glossy or matte photo paper.. it has the optional battery pack and internal Bluetooth dongle, and I didn't pay a cent for it, since, when I got it, I was writing for an online tech site, and reviewed it.. Canon told me to just keep the printer, which, optioned-up the way mine is, retailed for around $600.00.. so, ink.. the iP90 uses *tiny* non-refillable ink tanks.. the print head is not built into them.. instead, it's part of the ink-tank-holding assembly, so unlike some printers, you don't get a new printhead when you buy new ink.. because it's a very small, portable printer, the ink tanks are so small (it takes one black, and one tri-color tank, and MUST have one of each installed, or it will not print at all).. they don't last very long, depending on how much I print..
When I got the printer brand new from a Canon PR guy, he told me he'd not only let me keep it after reviewing it, but he'd send me free ink "forever".. well, "forever" lasted about a year, because Canon transferred him to a different division .. so I was left to fend for myself, when I ran out of all the free ink he had sent me..
He also told me to NEVER use third-party clone of Canon ink tanks in the printer, as it would foul the printhead and void the warranty, which is long-gone anyway..
Retail stores, and I don't care which one you name, sell the iP90 ink tanks packed two black, or two tri-color to a box at insanely high prices.. full retail, plus tax, plus the gasoline to drive there and back, and I will not pay their prices.. I will also NEVER use lower-grade third party ink tanks in it..
What I do is buy genuine Canon ink, sealed in the original Canon packaging, on eBay.. there are a bajillion sellers who offer it, and I simply search for "Canon (ink tank model number) genuine".. it's the word "genuine" in my searches that eliminate all the crappy third-party / no-name ink tanks.. then I do a sort by lowest price including shipping..
Typically, this method of buying new ink tanks saves me at least 50% or more off what I'd pay for exactly the same thing at any store you'd care to name, whether a physical store, or online..
As long as the seller has high positives, I'll trust them..