So, heres what we have found.

Leader price has two brands of Champagne for 12E and 14E.

Super U Marigot have large number of Brands including Laurent and Perrier (LP) for 28.95E

Petit Casino sells LP for about 45E

A Grand Case restaurant has LP for 95E

The Leader Price brands are good but the LP is better.

LP in the states is usually $45-60 bucks for us