I'd highly recommend a DIY kit like the "Universal Inkget Refill Kit" as seen on tv. It was on sale for just 9.99 at Fry's and can refill any brand and any model.
It comes with an injector needle syringe, print head cleaner, blue/magenta/yellow and some plugs and screws.
It took me under 10 minutes to refill my Compaq color printer. It's very simple to just pop the cover off and then use the syringe to pierce the sponge and fill the cartridge with ink. If you're skilled enough to work with a syringe without stabbing yourself and a razor it will be easy.
Just follow the directions and start with the lighter colors and clean the syringe thoroughly after each use and you won't contaminate colors.
One difference I did notice was that my blacks are marginally lighter than before. But with enough ink for 3 refills or more for $10... I think it's worth it since now I can print pages and pictures like a prodigal madman.