Not to barge in here because I would go to one in wash. even tho I am in Oregon. But I think a lot of the problem with this year is that the oregon swap has been planned for a year and everyone has already paid for their booths and/or made arrangements to go. Its really far south so people have had to put planning and time into going to it. I think a swap in washington would be a good idea for next year but this year, especially being in october when the oregon swap is the last weekend of october, is not such a good idea if you are trying to generate a turn out. I know a lot of people from washington even northern wash. who are already attending the oregon swap.
If you planned something to be in early spring like march over spring break or something, it would be a good way for people to sell their fall chicks to make room for their spring hatching chicks and sell their early ones. You would probably get a much higher attendance of both vendors and shoppers. Then people could also sell some of the goods they made over the winter stuck inside. I would suggest an indoor location with access to power for heat lamps tho.
Just offering some friendly advice since this thread seems to be pretty dead. : ) Hope it works out so I have another swap to attend next year!