Darden has a deal in 500, so that's what I'm going with. I think 250 would be enough, but it's only $5 more for $500. I think it's a useful piece of the recruiting puzzle. I think the process will work something like this:
1. Companies hold some type of info session, either for the entire school, or some subgroup like a club or something.
2. You go, listen to their spiel and then chat with some of their representatives. I would be useful to hand them a school-notated business card at this point. They'll probably hand you one of their cards, and you can help yourself by jotting down a few brief words that will help you remember this person.
3. You write a thank you email within 24-48 hours, referencing something memorable from your conversation with each person. If they have your business card in front of them, they'll probably jot down a few notes about you.
4. Many of the larger recruiters will come back to campus a few times, inviting their preferred candidates to cocktail hours, dinners, etc. As I see it, they will be more likely to include your name on that list if they have your business card in front of them.
5. After these events, they'll form a close list for interviews, inviting their favorites.
I think that keeping your name on their minds throughout this process is a key to success. A business card is one way to help them remember you.