Went to Valras Plage about 10 years ago ad as I recall the sea was very flat and lifeless compared with the Atlantic at Biarritz for instance. The Med. will have a different range of fish from this country so best do a bit of research on what you want to catch and how (beachcasting, spinning, float fishing, etc.)
All of the big supermarkets stock a fair bit of reasonable quality gear and some stock bait of sorts. Decathlon, the big sports store is probably your best bet. They are all over France an cater for most sports but seem to concentrate particularly well on regional trends like rugby and surfing in the south-west, coarse fishing, water sports and outoor activities in the Dordogne, etc. They also are pretty knowlegeable, unlike this country, about what they sell and most of the staff speak very good English.
Best of luck