This research was conducted in shops self-service of Pachuca and local commerce of Zacualtipán, were recorded prices of 24 products: rice, tortilla, tomato, lemon, jalapeno chile, milk, eggs, ham, sausage, beef, chicken meat, toilet paper, soap powder, toilet soap, toothpaste, beans, onions, potatoes, avocado, orange, banana, oil, salt and sugar. The dates for consulting prices were: July 26, 2007, on January 25 and May 29, 2008. The importance of this study is the comparative analysis and trends in prices. The shops self-service offer 9.7% cheaper in 62.5% of the products. The local commerce offer the 12.7% cheaper than the shops self-service in beans, onions, potatoes, avocados, bananas, oil, salt and sugar. During the July 26, 2007 to May 29, 2008, prices increased 19.8% and 19.6% in local commerce and the shops self-service, respectively.