Like JB said, lots of cash. Lots of opportunities there that you'd hate to miss out on because you only brought cards or not enough cash. If you see something you really want, buy it instantly because it likely won't be there if you decide to think on it or "come back later." It's a fast and furious pace with the smaller table vendors with all of the foot traffic, but you can find some real hidden gems in the mayhem. Bring a good bag that you can easily put your 10lbs of free swag into, water, comfortable shoes, and your pain killer of choice. It's a lot to take in and there are always booths I forget to visit, but it'll be a blast. Lots of raffles and gaws, can't wait.