I was on a tight budget on the Norte, so trolled ebay before I left and bought equipment cheaply, and made do with what I could beg or borrow for a pack, sleeping bag and hiking clothes. When on route I saved money a few times by cooking up what was in the free sections in alberge kitchens, people often leave uncooked pasta rather than carry it, so a tin of tuna and some tomatoes and an onion added to it made for a cheap and filling meal. Carry your own instant coffee, tea and sugar, and brew up when you arrive which keeps the caffeine cravings at bay cheaply. I formed a camino family and quite spontaneously we started cooking meals and eating together, which meant we had good meals with the economy of scale of buying for several people. Staying in Donativo alberges helps, but do try to leave a few euro. Some alberges have fruit with the meals, save it for the next days hike. Bread is cheap and filling, local cheese is expensive, but there are mass produced ones which are cheaper, carrying some bread, cheese and fruit, means you will not go hungry if you arrive and the only option is an expensive meal. I tried to stick to 20 euro a day, and provided I didn't spend too much at the bar in the evenings found that this was manageable.