It may not be the best online booking offer out there, but it has to be one of the most consistent. In order to move members away from online discount brokers, America West FlightFund is offering 500 miles and no booking fees for every roundtrip booked at http://www.americawest.com.

The program points out that Internet discounters like Travelocity, Orbitz and Expedia charge between $5 and $10 per ticket.

Key to the offer is its ongoing nature. Nowhere in the terms and conditions is there an expiration date, which makes the offer fairly unique. While online booking bonuses are nothing new to frequent flyers, only Delta, Southwest and US Airways are actively advertising them. US Airways Dividend Miles’ bonus — 3,000 for your first online booking and 1,000 for each ticket thereafter — is slated to end on March 31.

Southwest Rapid Rewards, of course, is still offering a bonus credit for online booking, but that, too, is scheduled to end, this time on April 1.

Delta’s comes closest to matching FlightFund’s — in fact, it beats it. SkyMiles members can earn 1,000 miles per online booking, and Delta is also removing any direct ticketing fees.

Experience has shown, though, that SkyMiles members are SkyMiles members, and FlightFund members are FlightFund members — the two programs are so vastly different that direct competition rarely comes into play.

In any event, both programs deserve kudos for continuing to migrate members to the Web at a time when cost cutting is at a premium.