There are many ingredients but most of them, at least here, are very cheap. Potatoes, eggs, onion, garlic and flour were typical and cheap ingredients and still are now.
Olive oil is not so expensive in Spain and as you can see it can be made without saffron. You don't have to add much saffron either, just a pinch. And believe me, there is always some wine or brandy in Spanish houses haha.
In my grandmother's time these ingredients were the ones grown in the countryside so they had easy access to them.
You should try to make it, it is delicious and you can make it with sunflower oil and if you don't have wine, you can make it without wine.
This kind of recipes are made with what you have at home, you can't always have all the ingredients.