Help, the printer is out of ink!

Have you ever noticed that the printer runs out of ink just before you need 100 copies of something important immediately? This weekend the black cartridge went kaput, it had lasted about 2 years, an amazingly long time in the life of ink cartridges around here. Late last night I made a run to Freddie Kroger and bought a new generic brand cartridge. Brought it home, installed it and it wouldn't work. Went to the website for help, still wouldn't work. Today I made a trip to the big box store and bought 2 brand-name cartridges. Thought I might as well pick up a color cartridge too, WRONG! They only had black cartridges for this printer, no color, what "store buyer" thought it was a good idea to only stock black cartridges for printers that also print in color? I would really like to understand the marketing philosophies in use in retail stores today.