An affordable airfare - as amazing as one offered by American Airlines to St. Croix in the U.S. Virgin Islands - are quite rare.

The carrier initially offered a $223 round-trip rate to St. Croix on Wednesday of this week and it’s still available to book today (3/29). But make haste. This offer does not have a ticket-by date which indicates that it could vanish at any time.

The rules to qualify are simple. An advance notice of travel is not required, so trips can be started as soon as this weekend (based on “O” space availability).

Travel at this rate is permitted any day of the week. Travelers must stay at least any two nights.

The last permitted day of travel at this low rate is Feb. 22, 2014.

Of course a few year-end blackout dates apply: Dec. 15-Jan. 15 south and Dec. 15-Jan. 12 northbound.

American serves both islands with a flight connection in Miami.

The U.S. Virgin Islands are U.S. territories, so travel to this region is just like crossing a state border. A passport is not required for U.S. citizens. Travelers over age 18 require to present a valid and unexpired driver’s license, state-issued photo ID, passport, or government employee ID; or two forms of non-photo ID, including at least one that has been issued by a state or federal agency.

However, if you venture over to the British Virgin Islands (such as Tortola, Virgin Gorda, Anegada, Jost Van Dyke, etc.) you’ll need to present a valid passport, Passport Card or other secure documents.

Sale airfares are always subject to change. Every seat on every flight is not offered at the lowest rate.

I recommend starting the search for available seats at Kayak.com vs. calling an airline directly. You can also search for the sale at travel websites such as Expedia, Orbitz or Travelocity, etc.

Airlines can discontinue or pull a sale price without notice when the offer does not have a “ticket-by” date or when the offer is deemed “sold out.”

Clara Bosonetto is a retired travel consultant.