Check with your local office supply, printer, kinkos, etc. for suggestions on what stock to use. I purchase a custom 'marble print' card stock from a local paper warehouse for $33/ream (250 sheets). Since I also set up my cards 8/page (in Word) and have them printed (b&w) and cut at the local office supply, my biz cards end up being really cheap (approx $8/100 cards) and I can 'change them up' whenever the mood strikes...
