I tried the 'Kerné' brand of cider while in a creperie in Finistere.
It was quite simply the best cider I've ever tasted.
The cidrerie production site is actually not in Plozévet, but very near, in Pouldreuzic. Here you can also purchase the delicious Kerné apply juice and regional honey (I bought both, just to be safe). However you may also find it in some supermarkets in Brittany and certainly in a lot of the creperies.