One of those standard, almost obligatory attitudes that you are supposed to strike up in Lourdes is to look down your nose at the "terrible commercialism". I don't go for this. People need to work in order to live and support their family; one way of earning a living is to run a shop. You could sell immodest clothing, useless artefacts to encourage vanity, or you could sell rosaries and statues.
The real biggie is the Palais du Rosaire with rows of rosaries, pictures, statues, medals and prayer cards. Everything is quite cheap and there is no sense that they are exploiting the tourists and pilgrims. All your rosary case needs can be comprehensively met here. I do admit that some of it is over the top - the pastilles made with genuine Lourdes water or the Lourdes flicknife, for example.
I go to the caisse with a large multi-coloured rosary (just couldn't pass it by), a small crucifix (so I can have the western iconostasis at Mass here), a Lourdes key-case (why not?) and the latest Lourdes gadget - a collapsible plastic cup. This can be handily carried on your visits to the grotto and frees you from that trying-to-scoop-up-water-in-your-hands misery.
If you want to feel superior, you can cross the road from the Palais du Rosaire to the shop that sells expensive statues, pictures and (probably) icons. That doesn't count as "terrible commercialism" because its a bit posh and pricey.