Through August 31, 2012, Starwood is offering a 20% discount on the purchase of Starpoints. The normal cost to purchase points is 3.5 cents each, so through this promotion they’re charging 2.8 cents per point.
Points can be purchased in increments of 500 points, up to a maximum of 20,000 points per account per calendar year. You have to be a member of the SPG program for at least 14 days in order to take advantage of this promotion.
So is it worth buying points at 2.8 cents each? Unless you have a specific need, probably not. Starpoints are the most valuable points currency out there, in my opinion (I value them at 2.2 cents each), but points valuations vary wildly.
Keep in mind that Starpoints can be converted to many airline currencies at a 1:1 ratio, and for every 20,000 points you transfer you get a 5,000 point bonus. That means that purchasing 20,000 Starpoints for $560 would earn you 25,000 miles with a number of programs, at a rate of ~2.25 cents per mile. While still not a spectacular value, in many cases it’s cheaper than you can purchase the miles directly with the airlines.
It can also make sense in some cases when a Cash & Points redemption is available, whereby you can use a combination of Cash & Points for a hotel stay, especially now that award stays count towards status.
So while this isn’t a rate at which I’ll purchase points, I know some people like to stock up during these 20% off promos.
(Tip of the hat to Loyalty Traveler)