A few years ago, pre banking meltdown, we stopped visiting one of the "best" restaurants in Pézenas - hardly high praise given Pézenas has always been a dining minefield. The house wine, that I discovered retailed at under €5, reached €20 making the mark-up on the trade price scandalous. Even more galling was that this neo-bistro (l'Entre Pots, now with new ownership) didn't have to fund such overheads as swish service, linen table cloths and flash stem-ware.
A fairer and more transparent system is to operate a fixed mark-up, the "droit de bouchon". In France, wine bars invariable double as a caviste, café and informal restaurant and the norm will be to typically add €7 to €12 on to the caviste price. Only expensive/rare bottles will be understandable exceptions to reflect the risks. To be fair, many restaurants that take wine seriously operate something closer to a fixed mark-up and value can be found with more expensive wines.
Drink locally is a tried and tested restaurant tip in wine regions. For a start they should be a match for the food and will invariably be sourced directly from growers and often at wholesale prices. Spot these and everyone wins.
I came across this faith restoring example at L'Ami Paradis, a new seasonal café resto at Mourèze in the Lac du Salagou area. Putting aside the fresh and tasty lunch (the main course "les burines" is stuffed courgettes) their short wine list represents near caviste prices. I'm not familiar with Domaine Campaucels. Trois Terres is seriously local and all about maximum Languedoc oomph. My (biased) pick would be the Ribiera Causse Toujours.
I put the 31 days in June down to post France World Cup celebrations.