The AS website uses points.com. Clicking "Buy Miles Today" here:
http://www.alaskaair.com/content/mil...ePlan-transfer
gets you:
https://buy.
points.com/PointsPartnerFrames/partners/alaskaair/container.html?language=en&product=BUY&CAMPAIGNCOD E=ASBGTLandingBuyBody&c=ASBGTLandingBuyBody