Las Vegas deal: $40.68 round trip from Long Beach on Allegiant Air

To promote its new service between Long Beach and Las Vegas, which will start Dec. 15, no-frills airline Allegiant Air is offering round-trip tickets for less than $45 --with a big caveat. And you have only a few days to buy your ticket.

The deal: Fly round trip between Long Beach and Las Vegas for $40.68, fees and taxes included. However, to get that price, you must purchase tickets at an Allegiant counter. In the Los Angeles area, that means going to either Long Beach Airport (LGB) or Los Angeles International (LAX).

Buying online incurs the airline’s annoying “convenience fee” of $14.99 per passenger. Booking by phone seems silly, since it adds $44.97 per round trip in convenience fees, more than doubling the advertised, bargain-basement fare. Also, be prepared to tack on $35 per bag for anything other than carry-on – probably not an issue for a weekend in Sin City.

Allegiant’s new service will be four times per week: Sundays, Mondays, Thursdays and Fridays.

When: Good for most dates from Dec. 15 through Feb. 16. Prices are slightly higher for New Year’s weekend. You must book by Saturday.

Tested: The deal appears to be available on most days. Allegiant’s only competition in the route is JetBlue Airways, which offers daily service.

In an online search of round-trip fares to Las Vegas for the Martin Luther King Jr. Day weekend in mid-January (Friday evening – Monday morning) I found Allegiant charging $40.68 (when booked in person) out of Long Beach; JetBlue charging $157 out of Long Beach; from Orange County (John Wayne), Southwest was asking $187; and from LAX, I found fares starting at $141 on the search engine Kayak.com.

Tip: Don’t be misled by the fine print on this deal on the Allegiant website, which seems to indicate that a hotel purchase is required to get this airfare deal. It is not , according to Tyri Squyres, the airline’s vice president of marketing and sales.

Contact: Allegiant Air , (702) 505-8888. (Note that you’ll be charged extra fees for either online or phone bookings, as mentioned above.)