When I walked from Ferris in May 2019 there were maybe two souvenir shops selling overpriced (€5) shells. I'd heard on a podcast there was a self-service shell stand that operates on a donativo basis some kilometers outside of Ferrol.
Sure enough, an hour or two outside town we came across a display of shells on cords hanging off a signboard above a locked cash box. No suggested donation posted, give what you want. Two styles on offer: traditional plain shell with Cross of St. James and a secular shell painted blue with a yellow arrow. Both were on a silk cord.
I left a few Euros in the box, chose the shell I liked best, tied it to my backpack and continued down the path.
I believe I saw at least one (maybe two) more stands like this along the Ingles.
Another lovely thing we saw were the impromptu refreshment stations set up by locals in strategic locations, offering a few chairs or a bench, some juice, cookies, a trash can, and even a guest book, with a secure cash box mounted nearby. Prices not posted, give what you can or think is fair.
Nice way to support the locals who are providing anonymous comfort to pilgrims on a Camino whose infrastructure is still developing or lacking in some areas.