I have an offer in my UA app for 95% bonus when buying miles, the promot code is JULYBUYMILES95, good until July 28 (so 2 more days).
Not sure if this is a personal offer, or whether others can use it. If you feel that UA miles are valuable - try it out.
(Me, I'd rather buy LM or AC - way more valuable, UA mileage redemptions are the most expensive of the above and partner availability is very poor)