Between October 15 and November 30, 2012 you can purchase starwood points at a 20% discount. This means 1,000 points will cost you $28 instead of $35.
You can purchase points in increments of 500 and up to 20,000 per calendar year. Points can take up to 24 hours to deposit into your account and you must have your SPG account activated for at least 14 days.
Remember though, when you use points, you will not earn points on your stay or any bonus points if there is a promotion. You will, however, earn stay/nights credit, which is great!
You can
purchase points here.