I have that wonderful Trader Joe's instant coffee. I don't drink coffee everyday, only if I need the caffeine. If I have a test that morning and I need the caffeine though, I'll probably be drinking some higher quality oolong.
Even worse than using the instant though is that often, I don't even 'use' it. I just dip in my spoon, and shove a heaping teaspoon in my mouth. Lazy man's caffeine pills.