Alaska Airlines Mileage Plan runs a number of offers throughout the year and right now, instead of giving bonus miles which is typically the norm, they are offering a flat 30% discount on Alaska Airlines Mileage Plan mile purchases when you buy at least 20,000 miles before the end of 30 June 2019!
Alaska Airlines Mileage Plan miles can typically be purchased at USD 27.50 per 1,000 block but with this exclusive 30% discount, the price will go down to just USD 19.25 per 1,000 block. Do note that there will be a tax recovery fee of 7.5% which will be levied onto the final amount (as per usual business) so this will effectively take the cost up to USD 20.69 per 1,000 block.
You should already know this but Alaska Airlines Mileage Plan miles are great on Japan Airlines in Business Class - you typically can fly to two destinations in the region (one of them has to be Japan) for just 25,000 Alaska Airlines Mileage Plan miles. As an example, you can do Singapore to Tokyo (Haneda) and then Tokyo (Haneda) to Bangkok with just 25,000 miles which will set you back approximately USD 517.34 (SGD 700). That's two business class flights on Japan Airlines for SGD 700! Even after adding the applicable taxes and partner fees, the total will add up to approximately SGD 800 which is an amazing price to pay for two flights (even in Economy!).