I think most counties in FL ban alcohol sales before 1:00 on Sunday. Plus most counties have cutoffs every day, some as early as midnight but most until 2:00 am. Otherwise, most grocery stores sell wine and beer and some even have liquor stores attached. It's just a matter of what kind of license they get (Florida liquor laws allow for 2 different licenses; one for just wine and beer and another to sell wine, beer and liquor).
Goodings has an excellent selection of beer, including lots of microbrews and imports. I was surprised to even find some Belgian selections. The beer selection in Florida has improved greatly since they lifted the bottle-size restriction last year (used to be you could only sell 12, 16 or 32 oz. containers - lots of imports and micros come in off sizes). They also have a decent wine selection.
I've never seen a 30 pack in FL. Cases are 24, though, so that should get you pretty close.