Had a nice one last month and (again) picked up some stuff that will likely cover my expenses once sold.
Next time I might go real early (have to be a member to get in ahead of the rest of the crowd), spend time rummaging through boxes first and then the remainder of the day photographing the salesmen and visitors in the hall. Sort of a one-day portrait/project of the Fair.
After that I think I've seen enough Fairs to last me a while.
Still, I can recommend it to anyone who never went to one before!