Not sure where you're from, but those seem like typical prices for cities that are a few hundred miles apart in most areas of the world. In the US, Southwest offers one way fares for $50 sometimes, and they tend to be one of the more expensive US airlines. I often find one ways out of Chicago for ~$100 on United and American as well.
How (and whether) airlines make money is a different story. Many of the discount carriers make it in ancillary fees, such as charging for a water on the plane (which surprised me once on Aer Lingus).