Money
Spain, in general, is not an expensive country to live in. Even though there are several differences within its regions, many foreigners are able to enjoy the country that much because they can have access to food and leisure at a really cheap price.
Living in cities like Madrid, Barcelona or San Sebastian can be up to 40% more expensive than other interior regions of the country.
So, even though the Spanish territory, in general, has lower prices than the vast majority of EU countries, this big cities can distort a bit the comparison.
According to the OECD Better Life Index, in Spain the average household will spend "22% of their gross adjusted disposable income on keeping a roof over their heads, above the OECD average of 20%".
Take a look at the Eures Portal to get an idea of the average of the various prices in Spain.