Through December 21, 2012, Alaska is offering a 30% bonus on the purchase of Mileage Plan miles.
Mileage Plan miles ordinarily cost 2.75 cents a piece, plus a 7.5% federal tax, for a total of ~2.96 cents per mile. Through this promotion the cost of purchased miles is brought down to ~2.27 cents per mile. This isn’t quite as good as the 40% bonus on purchased miles they were offering in September, though if you’re just looking to top off an account, this promotion is worth keeping in mind. Alaska does have some amazing partner award redemption opportunities, after all.
(Tip of the hat to Todd)