American is offering tiered bonuses on the purchase of AAdvantage miles through January 31, 2014. The bonuses are tiered as follows:
So to max out this promotion you’d want to purchase 45,000 miles (since that essentially gives you a ~33% bonus on the purchase of miles). If you do that you’d be purchasing a total of 60,000 AAdvantage miles (45,000 miles plus a 15,000 mile bonus) for a total of $1,365.31, which is ~2.275 cents per mile.
As a point of reference, last month American offered up to a 50% bonus on the purchase of AAdvantage miles, making them roughly two cents each. While American and US Airways miles can’t be combined yet, US Airways frequently offers a 100% bonuses on the purchase of miles (bringing down the cost to ~1.88 cents per mile), and occasionally offers a 100% bonus on shared miles (bringing down the cost to ~1.1 cents per mile).
So this promotion certainly isn’t one I’d take advantage of as a means of speculatively purchasing miles, but at the same time if you have a specific use in mind this could make sense. But we’ve definitely seen better offers in the past and I’m sure we’ll see better offers again in the future.
Mileage purchases usually take 1-2 days to post, though American allows five day award holds, which means it’s possible to hold something “risk free” while the miles post. Also keep in mind these purchases are processed by points.com, so wouldn’t count as airfare spend for the purposes of your credit card.