In central Florida's Tampa Bay/St. Pete area I'd suggest you visit the Sound Exchange on Nebraska Ave in Tampa. Mojos Books and Music in Tampa is great for vinyl but not so much for cd's. St. Petersburg has several good ones, just Google "used music cd's St. Petersburg Fl." If you're looking for an interesting place to sample southern food and Americana music in one location, check out Skippers Smokehouse in Tampa (they're real close to the Tampa Sound Exchange location.) Skippers is a local institution on the music scene and the restaurant is a real quirky funky joint. Their website lists their concert schedule.
https://www.skipperssmokehouse.com In Orlando, I'm not that big a fan of Rock N' Roll Heaven but they've been there a long time so lots of other people must like their music selection. Park Ave Cd's in Winter Park has been an Orlando area music scene stalwart for many years as well.