Wow, didn't know they actually do that to have such a price difference :o
Was it a regular / hypermarket carrefour? As we have a Carrefour express around the corner and there the prices are much higher as well. The shop owner is an independent and is opened 7 days out of 7, while 'normal' supermakets are often closed sunday afternoon and sometimes monday before noon.
But yes, eggs, if prepared well, I really love them!