It is more of a selling or buying thing versus a true "swap". While I am sure there is some swapping going on, the vast majority are selling their corals. So, you do not have to bring anything, except maybe your wallet if you want to buy something.
If you have a large amount of corals to sell, you should rent a table (I think $20 or something like that). If so, you have to bring everything (tank, water, bags, lights, etc.) If you have just a few, the club currently has plans to have a table where club members can sell them together. I think someone has volunteered to lend a tank or two, but they will need voluteers to bring prepared water, bags, lights etc. They will also need people to volunteer to take a shifts at manning the tank sales. I have volunteered to take a shift at the club tank.
For anyone that hasn't been to one, it is very exciting to be able to see so many tables with such a wide variety of corals (softies, LPS and SPS). There will aslo probably be someone selling aquarium supplies and equipment. If your are a reef addict, like most of us club members, it is like a "kid in a candy store".