A denarius was roughly a day's wage during this period, so the prices mentioned in the text represents a severe famine. A man would have to work all day to get enough wheat to feed himself. If he had a family to support he would need to buy the cheaper barley. Given the large size of families in those days, the children would likely die or be stunted by malnutrition.
Why does the text mention sparing the oil and the wine, items less necessary for life than grain? In Asia Minor of the first century A.D. this text would have connected with a hot issue. Wine trade at that time was more profitable than grain. The wealthy landowners of Asia were, therefore, switching from grain to grapes.
So property owners dedicated much of the land in the province of Asia (which included the seven churches) to producing olive oil and wine for profitable export. Meanwhile, the cities of Asia had to import grain all the way from Egypt or the areas by the Black Sea. So while landowners and shippers profited from their choice, the people in Asia had to pay higher prices for staple foods.
The problem was serious enough that the emperor Domitian tried to intervene and force the landowners to restrict vine production in such places as the province of Asia. His attempts were extremely unpopular and proved unsuccessful. If he had succeed, it would have been quite a blow to the wealthy of Philadelphia, especially those who gained their wealth from vine production. As is often the case, the greed of the wealthy had serious consequences for the poor.
But we could also read the sparing of the oil and the wine as a token of God's mercy in the time of judgment. Ancient Mediterranean warfare included destroying the standing crops in the fields, but not the vines and the olive trees (which took more than 15 years to reach productive capacity). The loss of wheat and barley meant hardship for a year, but eradicating vines and trees would result in enduring disaster.
While the judgments of God in our lives can be severe, they seek to redeem us, not destroy us. It is not God's purpose to prolong suffering, but to use difficulties to get our attention and bring us to a place that would be better for us. If everyone were more attentive to God's call much of the injustice in the world would disappear.
Lord, I want to be attentive to Your call in my life today. May I not need overwhelming difficulties before I am willing to listen to You.