Okay here's the question for photo printer owners: I'm deciding on what to buy by looking at the price of the printer AND the price of the cartridge. Some of the Canons have a single color cartridge while others have different colors. What's better? i'm thinking, one is cheaper. On the other hand, if say I print tons of yellow and the yellow runs out, i could just replace one out of five instead of replacing the whole set? what do you think?