I got the 5"x5" tri-fold cards made from WHCC. I'll be handing those out at a show in October. They look nice. In the end it costs me like $1.80 for each card. If it helps me book 10 clients (i hope!), $18.00 (plus the cost for the show) for $50K in sales isn't a bad ROI.
I second the double side postcard, I use the 8.5x11 size. Good value. The rounded corners are a nice touch also.At overnightprints.com they are about $99.00 for 500.
Whatever you decide to hand out, make sure it looks professional and, more importantly, unique. There are scads of photographers at bridal shows, so you need to do something to stand out from the rest. I had my booth set up to look like a living room, complete with walls, big enlargements, chairs, a nice mission style coffee table and sofa table, a projection screen, carpeting, and baskets full of chocolate to entice chubby brides.
