The question was:
What happens if you arrive to a municipal albergue and it’s full? For instance I get to Roncesvalles (I know that one is large, but just the first one that came to mind) and it’s all full? Will other albergues/hostels be more expensive? Will I have to shell out big time for hotels? How would I find other albergues/hostels, and what if they’re full? I’ve no idea how common it is for them to be full, just wondering.
Read all the good advice on what do do if the albergue is full when you get there.