I ran out of 500 business cards early on, last time (2009); had to keep making and bringing in more cards, postcards, etc. as time went on. Was almost completely cleaned out by the end of the show. It's a good idea to check on things every week or two--- if you have your volunteer shifts scheduled a couple of weeks apart, bring some extra cards with you in case you find you've run out.
Remember: over 70,000 visitors in 2009! This time I've got 1500 cards on order. If they aren't all gone by June 24th, I can use them elsewhere, 'cause I kept them generic--- Name, website address, email address, one featured artwork. And for what it's worth, I use Overnight Prints. They've always done a good job, used better paper stock than their competitors, and prices are great, especially when they're having a sale.