excellent posting. the demographics matter, a whole lot. La Sirena might be able to sell butter at 80 peso, while the comado sells it at 90. however, the average guy maybe wants 10 pesos worth,and that you cannot get at La Sirena. also, if one checks closely, the prices at La Sirena are no great shakes. smoked herring fillets 89 peso per tin, 59 peso in the average supermarket. i have seen several such eye opening discrepancies. you look good shopping there, and coming out with a nice yellow bag. your wallet feels the pinch.