A visit to the Le Clerc superstore located in the Oceane centre at Gonfreville L'Orcher is worth it just for their wine section. They have a proper cellar at the back which contains wines that mere mortal have heard of but often cannot afford - Chateau Lafite sir, a snip at anywhere from 70 Euros upwards. Lots of old wine as well - way back to the early 1900's, and all for sale at a price.

I regularly travel from Caen up to Le Harve as it is the cheapest place for several types of wine and champagne. Moet & Chandon is about 5-10 euros cheaper than in Caen depending on any offers, so if you're buying a few bottles its worth the trip.