The use and cost of inkjet ink never ceases to amaze me. I'm glad the the HP Photosmart C6250 (which has given me a lot of problems to solve) uses individual color cartridges. I really don't understand how each color is used by my specific usage pattern. But, I am surprised that it looks like it is cheaper to buy indivdual HP 02 cartridges rather than the entire color pack (black ink is no longer included in that pack). I think someone estimated that inkjet cartridges costs something like $8,000 per gallon. So, I wish I could get a better handle on how it is actually used in my printer (given the kinds of things I print).