Hi Craig,
We're also off there soon and I've been looking without much success. I know that the trip to the local shop(s) is not worthwhile from previous holidays.
I found this site: https://www.railserve.com/events/train_shows.html and they list the shows/fairs etc. Most of the Florida entries I've seen have been the wrong dates for us or too far away. I don't know if this one is any good for you:
61st Florida Rail Fair Saturday, October 7, 2017 Volusia County Fairgrounds DeLand, FL
and I've got no idea what would be there!
However, there seems to be a good number of entries for Florida.
Andrew