US Airways has a new buy Dividend Miles promotion between May 3-25, 2014, for up to 100% bonus on purchased miles (max 50,000 miles).
US Airways will likely have a staggered bonus that maxes at the 100% when you buy the maximum or very close to it.
You can access this offer here once it has been activated on May 3, 2014.
The price of a mile, when purchased at the 100% bonus, should be 1.88 cents each.
Seems that the US Airways will continue these mileage sales until the very end. This is the maximum bonus that US Airways usually offers for straight purchases. You could have purchased miles at 1.1 cents during the 100% transfer bonus.