We, in Canary Islands have a different type of VAT (Value Added Tax) lower than the one that uses the rest of Spain. But, we also have some other taxes due to Customs. For these reasons, the price we see in whatever article in amazon.es is not the price we finally pay. This site helps you to calculate the final price, based on this information.
Just write below the price (in euros) you see in amazon.es and click the button. Then you will get the results. Note that we are not considering the costs for transport (added by amazon itself), and the products must be shipped from and sold by amazon.es, otherwise it could fall into aditional taxes.