Hi Lukasz: I know there are aftermarket chips, BUT for the sake of a superior and stable ink flow, essential to bubblejet print heads to prevent clogging and overheating, you still depend on Original Epson cartridges. The 550/551 series consist of 3 different sponge material (probably with different densities and porosities) to regulate an optimal inkflow and is certainly patented. So Canon has played the game very cleverly, so you still will have to a set of Original XL cartridges to start with and therefore...you will have to buy at least one set of them to begin proper refilling.
The setup 551/550 carts are just a joke to use and will run out of ink in a flash, then you have to purchase a second set this time XL carts which are as dear as the printer was itself.
Refilling these OEM XL cartridges is fairly easy but its pure luck when using them because you can’t see the level of ink nor can you reset the chip, (Fly by wire) and the printer responds by using many more excessive cleaning cycles.
This is the one time that compatible carts actually work better than OEM’s because you can refill easy, they seem to have good ink flow with a newer air vent system in them, you have ink level monitoring because the chip works, so all in all much better overall control.
Like Epson, Canon have made the use of their OEM 551 carts almost impossible to use, so it’s a case of using the next best thing possible which ironically turns out to be just as good of alternative..