I'm in the Tampa areas also, and they seem to be run in the spring. Island Nautical (a commercial
sail loft/gear retailer), it was reasonably sized this year. The City of Gulfport has one as well, also in the spring.
The Eckerd College one is apparently huge, but I've never been. I'm told the prices aren't all that great, as everything has been donated, and proceeds go to the college's Search and Rescue
Team. I don't begrudge them a dime, it's a great program that help a LOT of boaters.
There is also a large one in the Bradenton area, can't remember the name. Also in the spring of the year.
If you need something at a reasonable price
, and can't wait, I've had good luck with Don's Marine Salvage
in Clearwater. Bought some hard to find Bomar hatch parts