FYI: Alaska Mileage Plan bonus now on:

Buy miles from August 26 – October 14, 2014, and you'll get more miles for less:

Buy bonus:
5,000 - 19,000 miles, get a 20% Bonus
20,000 - 34,000 miles, get a 30% Bonus
35,000 - 40,000 miles, get a 40% Bonus

Nice long window too!