I've done several book signings in the past, all with varied success. My usual operating procedure is to have my Eppie Award on display, provide bookmarks to pass out, offer a variety of candy and sell my books for $10.00 each.
I buy my books from either Lulu.com or Amazon.com at full price. I usually buy from Lulu when they are offering one of their sales as this generally covers the cost of postage. The reason I purchase at full price is so it will show in the count for my publisher or on Amazon. When I get my royalty for the sale, it makes the book less and fairly close to what I would have paid had I gone through my publisher.
That said, each book is about $11.95 or $14.95 so I either lose a little or break even. (I also have to pay state tax on each sale but that's nominal)
This weekend, we had a great turn out of the Houston Indie Book Festival. In a split decision, I changed gears. I sold my books for $5.00 each. Had I not set the price so low, I would have only sold maybe 3 but probably only 2. Most stopped and took a second look when they were told the price. I took a loss for each sale but ... I don't spend any money on promotional geegaws that most folks end up throwing in the trash. In my mind, the difference equated to promotion.
I always say, "one reader at a time." I'm hoping for a domino effect. If they read it and like it, they'll buy more. Most of the readers who bought, claimed they did not own an e-reader and preferred to read paper. They wanted to know if they could purchase more of my paperbacks from a bookstore. I directed them to go to the publisher's webpage or Amazon.
For the readers who didn't buy today, they went home with a bookmark and information and a reminder that first chapters were offered for free through my website or through the e-book providers like Amazon or B&N. I actually had 4 times the amount of traffic I usually have to my website.