My experience, Alberques 7-10€, pensions 15 to 20€ per person. Lunch 5 € p/0, dinner pilgrim meals 8 to 10€, you can pay more or less if you stay in a pension over an Alberque, have a fancy meal versus a pilgrim meal, although the pilgrim meals I had tbh were delicious. Breakfast because it's generally 7am or before I bought a bag of croissants each individually wrapped and a bag of baby bel cheese in a supermarket when I arrived and paid maybe 1€ for the bag of croissants and no more than 2/3€ for the cheese and I used these for breakfast each morn and if I got peckish along the way, these lasted about 3days. It really does depend on the person but can be done for 30€ a day each easily and less if you cook your meals, I just didn't choose that option but those that do can do a day for 10 or more less a day.
Buen camino