Beyond the lack of owner updates (and trust me, it can be hard to get responses to requests for updates from accommodations), there's also the particular challenge on the Norte of huge price swings based on season. There are places that charge 35 euros for a double in the dead of winter that are able to push the price to triple digits in the peak of summer. That's why you end up with something like "40€+" where the "+" is doing a whole lot of work.
It's a funny thing. On the Via Podiensis, for comparison, prices are much more stable month-to-month. In fact, when there is a shift in price, it's often in the opposite direction--with gites charging a little more in the winter because they have to turn on the heat. By contrast, tourists flood the Spanish coast, so accommodation rates on the Norte surge accordingly.