From now until 30 Jan 2018, you can earn up to 50000 bonus miles when you purchase miles from AAdvantage.
If you purchase the maximum cap of 150000, together with the bonus miles, the cost for each will only be 2.2 cents. Note that the bonus miles do not count towards the annual purchase limit.
AAdvantage miles are great for redemptions on Oneworld carriers. You can purchase your AAdvantage miles here.