For the last six months of 2012, American offered up to a 50% bonus on purchased miles. For a purchase of exactly 40,000, 50,000, or 60,000 miles that meant a price of 2 cents a mile, the lowest price I had ever seen American sell miles direct to consumer for.

Through February 28 that offer is back.

For A Limited Time Only: Earn Up To 30,000 Bonus Miles, A 50% Mileage Bonus
As we move towards the new American, and continue to modernize and innovate, we would like to share the excitement of our new look, with you – our valued customer. Now, through February 28, 2013, you can earn up to 30,000 bonus miles when you buy AAdvantage® miles.

This is a price at which I’m almost a buyer. I won’t be taking advantage of the offer since I have a seven figure AAdvantage balance (and a fairly large stash of US Airways miles as well…) so should do better holding my cash. But if I had a balance of, say, 200,000 miles I would probably buy to give myself nearly enough miles for two first class roundtrips to Asia.

The miles don’t post instantly, they say it can take 72 hours but usually takes less than that. Bonus miles don’t post right away, or with the purchased miles either, but can take up to 5 days.

The one challenge here I don’t like is the time to post the bonus. American allows 5 day award holds. That lets you put a reservation together before buying miles, so that there’s no risk involved that the award space will disappear after you’ve purchased the points but before you’ve secured the ticket. In theory you should be able to still do that here, that the bonus points will post before the reservation hold expires, but it’s still potentially cutting it too close for comfort.

Interestingly American used to cap mileage purchases at 40,000 per year but they’ve increased that to 60,000 and the increase seems to have stuck. That amount would seem to make it impossible to straight up buy enough miles (starting from zero) for premium cabin roundtrip awards to most places. But that’s not quite right.

American allows one-way awards so you can book one direction each out of two different accounts for the same person. Rinse, repeat for each person making the trip (with the caveat that especially if last names don’t match I’ve been asked on occasion to pay taxes using a credit card with name matching that of the accountholder).

Since it’s often a question, AAdvantage miles purchases are processed by Points.com so you won’t earn ‘airfare’ bonuses from the credit card you use to buy miles (such as Sapphire Preferred double points on travel, or American Express Premier Rewards Gold triple points on airfare).