Well! If you check it out, the price of each S80 is near 1 billion Euros. That means 4billion Euros for four S80s. (It was estimated that in 2012 the cost of 4 subs to be around 2.2 billion Euros)
Our 6 Reis class ships’ total cost, at the time of contract, was to be 2.06 billion Euros. So there...