Stiffler probably you didn't buy it in the right shops! However in Italy the cheapest drinks (compared to other countries) are water, coffee and cappuccino....of course it always may be the case that you find a mean seller that raises the prices for foreign tourists, however this should not happen for coffe and cappuccino because their prices is established by the councils and the bar should expose (by law) the correct prices that you can check.
You also have to consider that if you have some drink in a bar, if you drink it standing they have one price, but if you sit down and the weither serves you, then the price raises, and in some cases it raises a lot!