There are some really cute business cards posted here! As a graphic designer (and more specifically a business card designer) I certainly think cards are a MUST. If you sell a product, a card should go out in every package. If you go out on the town, some should be with you. You never know when a conversation for self-promotion comes up!
These days, you can have business cards custom designed to your exact needs for VERY little money ($5). Then you can print (or wait for specials) on many websites out there for cheap for 500/cards (under $20). There is really no reason with numbers like these that you can't have a state of the art business card design for next to nothing to promote yourself!