When I lived in WPB I went to this show a few times. It was very small and unless it has increased in size, it is probably not worth the drive from Miami. Just my opinion...
I've been to that show when I lived in the Deerfield Beach/Boca Raton area. I agree that it's not worth the drive from Miami.
If it's the same folks that organize the small local shows, they also organize shows in Ft. Lauderdale area throughout the year. That will be a much shorter drive, albeit still a relatively small show.
The website says 90 vendors for the show. Who knows, maybe it's changed? Check in with Ben Siegel, he would probably know best since he used to vend the WPB shows.