Ah... If it where so simple ;-}
Sadly, each company designs the printer head/tank so others can't be used.
You see, the ink is really how these companies make their money not on the printer!
Even still the ink formulation each uses is unique enough that one can't just re-fill just any ink into it. Some companies do offer re-fill kits or re-fill service for some models. Just be be careful here!