Unfortunately for any airline that sells its own miles directly to consumers—and most do, because it's a hugely profitable side business—US Airways has set the value bar prohibitively high with its recurring 100 percent bonuses.
Taking advantage of the US Airways' offer effectively cuts the cost of purchased miles in half, making them a good buy, even a great buy if they're redeemed for pricey business-class international flights.
By contrast, other airlines' bonuses for purchased miles, which generally hover in the 25 percent range, improve the value proposition only modestly.
This offer from Delta is a significant improvement over the average miles-for-sale promotion but still falls well short of US Airways'.
Through March 31, Delta SkyMiles members will receive a 50 percent bonus when purchasing miles for their own accounts or as gifts for other members.
The normal price of Delta miles is 2.8 cents each, plus a 7.5 percent excise tax, with a 60,000-mile annual maximum per account. Including the bonus, the per-mile price is reduced to 1.9 cents, plus tax.
Worth noting, if you're thinking of establishing a new SkyMiles account just to take advantage of this offer: "Buy and Gift Miles may only be received into SkyMiles accounts that have been established for at least 10 days and have earned at least one mile since enrolling in the SkyMiles program."
Deal or No Deal
For perspective, purchasing the 25,000 miles required for a round-trip domestic coach ticket (hypothetically, since sales are only in 2,000-mile increments) at 1.9 cents each amounts to $475, plus $35.63 in excise tax, for a total of $510.63. With the average cost of a domestic coach ticket—and one that's unencumbered by an award ticket's capacity controls—currently at around $350, it's hard to justify paying that much for miles.
Put another way, since US Airways' latest 100 percent bonus for purchased miles is also in effect through March 31, is there any reason to pay a premium to purchase Delta miles over US Airways miles, given that both may be redeemed for flights on multiple airline partners, to most corners of the world?
On the other hand, if you're already committed to the SkyMiles program, and just need a few thousand extra miles to top off your account, paying 1.9 cents certainly beats paying 2.8 cents a mile.
Reader Reality Check
Delta is selling. Are you buying?
This article originally appeared on FrequentFlier.com.