Today's clear plastic business cards can be awesome little works of art too. You can use any color under the sun and incorporate your logo and any design you can think of. I got one from an architect the other day that had a ruler along one edge, such a clever idea.
All the top companies are using them now, so if you want to give a prospect a card, why not give them the best? Cheap cards are better than no cards at all, but clear plastic business cards make an instant statement - we are a thoughtful company, we want you to remember us, and we know about quality.