As far as the 2009 Comi-con in San Diego, California, they said they'll post the exhibitors that will definitely be there, 2 weeks before it starts.
It's just there will be so many and we'd still need to contact them and wait for a reply.
Here's a list of the exhibitors that were there for the 2008 one:
Then there's the other cons like Shore Leave, Dragon*Con, etc. But I'm not quite sure which campaign members are definitely going to those.
500 is definitely not too many. Besides you could give some to various exhibitors that are willing to put some out on their booths for people to grab.
gatebuilders, are they going to have a season 6 order form on them?