Low cost airline Frontier has just launched an airfare sale with prices going as low as $19 each way. There are discounted flights available through April. The lowest fare is available even for Christmas break and during ski season in Denver.
USUnited Airlines are currently running a great promotion on their flights from Chicago to Los Angeles and vice versa. We've found a very affordable airfare on this route. You may book tickets from just $80.20 round trip.