We have looked at the discount sites, but found booking through the airline was cheaper. When we went to Vegas, the flight was the same price at the ATA website, or Travelocity, but Travelocity had a "finder's fee" type thing. My upcoming trip I booked through Southwest, $39 each way, Detroit-St. Louis.

I don'tknow if you would find the same thing ornot, but before you book anything, check the discountsites, then compare to the airline site. You may find the flight price is the same on either.