Hey, I'm from PSL and still have family there, so I travel down every couple months from Gainesville. PSL used to have an ok selection of stores, but the real way I got my collector pieces and deals was dealing with locals. In the past 1-2 years a couple of stores of closed/moved. I would frequently make the drive to Vero and go to Treasure Coast corals. The owner's name is John, very nice guy and I would recommend the drive once a month.
I visited St. Lucie aquatics last time I was in town, and they seemed like they will do well in time.
As for fintastic, im not sure what day during the week you went, but that was one of my go-to's for deals. You should sign up for their newsletter. Basically in the start of the week they are loaded up with a big variety, for VERY cheap. After 2-3 days they're usually cleaned out uuntil the next week.
There are a ton of reefers in that area though, just try meeting people at the stores or their FB pages.
As for clubs, I've been away from PSL for about 4 years, and we didn't really have one just for psl locals. I worked part time in petco while I was in school, fixing their aquatics section. That's where I met a lot of people. I'm sure there's a club or something now. You can pm me if you'd like, and I can text my buddies back in psl to see if there's any clubs or meets closer to psl.