Wine stores in South Beach?
Gulf Liquor on Alton and 17th has a nice selection at surprisingly good prices.
I am not sure about their selection of French wines; but their California Cab (the only type I know enough about to comment on) selection was excellent and well-priced. I needed a specific type of Champagne for a gift and their price on it (Laurent Perrier Brut Rose) was the same as at Total Wine in NMB.
They also have an excellent high-end beer selection.
I'd give them a shot.
Gulf liquor is a bit gimmicky (celebrity photos and the walls and bar in the back) but actually has an impressive, for Miami at least, selection of champagne. Vintage Pol Roger, Ruinnart blanc de blanc, etc. Took a quick peek at the wines and agree with the consensus. Not a large selection and prices on the high side. Good selection of spirits however.
Stopped by Epicure today and remembered they have a small, overpriced but nice french selection: 2005 Ganoux Pommard, 2009 Ghislane Barthod Chambolle Musigny, 2009 Remoissenet Pere et Fils NSG, Dujac Pere et Fils Gevrey Chambertin all $15-20 above average wine searcher prices but at least it's an option for South Beach.