I think it depends on what you buy. Prices of food change with events such as natural disasters which may disrupt the food supply, causing increases in food price. As increasingly more land is used for the growing of cash crops such as oil palm, decrease in food supply may result in increasing prices. Food that is in season tend to be cheaper as there is a large supply of them. Food that is rare is usually more expensive as it is difficult to obtain them. Locally grown or produced food than imported food as less money is used on transportation.
In Singapore, food tends to be a little more expensive as we can’t grow crops here due to space limitation. So most of the food we get is imported from abroad which results in higher prices.
It costs quite a bit to grow food, especially when we want foods that are not in season. Strawberries aren’t meant to grow in Britain in December! To grow those foods, we have to use greenhouses and keep them hot and provide more fertilizer and stuff.
Like Daphne’s said, locally grown is cheaper than stuff that’s had to come from around the world. And stuff that’s in season should be cheaper too.