I'm not sure I've been to a "swap" before - how does it work? It's not a "pay for a table" type of event is it?
Typically a swap is a pay for a table event for sellers and buyers pay an entry fee - just like a gun show, pet expo, wine expo, etc.
It is my understanding that while the auctions in Chicago are ho hum, the swaps are HUGE. i.e. 800+ buyers paying an entrance fee. How to get that same response here in Michigan is the trick. MCAS tried that swap 5 or so years ago. As a seller there I have to say it was horrible as I sold almost nothing - I took like 50 bags of fish on a day trip. A guy came down from TC with a ton of discus and didn't sell a thing either.
The only way to get one to grow is almost to just make it an informal free event for all and let it evolve. But the issue with that is there are always costs and who is going to pay them? Hall fee, advertising, etc. Someones gotta pay...