Pre-Painted Plastic
You know... if you don't care what your visuals look like and you're too poor to buy quality minis and paint them, then use cardboard, or paper, or plastic beads, or whatever your heart desires. But don't drag the rest of down into your visually "blech" games.
Quality pewter minis, pain-stakingly painted, show a deep level of commitment to asthetics and role-playing in general. Some people don't like to use the little green plastic army guys to represent a hobgoblin tribal adept and his band of acolytes. If you do, fine. But people who care more about that particular aspect of the game would like the oppurtunity to develop such an outlet.