Research Before We Buy

In Surabaya there is so much hypermarket like giant, hypermart, and carrefour. Their competition is also become more tight. The consequence they often compete to give lower price, and they also advertise their price in newspaper. But the question is, is it true that we can get the same price between the price in advertising and the reality in there? As customer, we must research because sometimes the price is not same that we look in newspaper. I personally have experience that the price in newspaper is not the same with the actual price from the label. Is it a cheat to inrease their revenue? Who knows?