Until today (December 31, 2016), you can buy up to 30,000 Starpoints with up to a 50% discount on the normal purchase price.

The discounts are targeted. To see your discount, sign into your SPG account at this link. I was offered the maximum, 50%, discount on purchases of 5,000 or more Starpoints, and I bought 20,000.

Starpoints are normally sold in increments of 500 points for 3.5 cents per point. Getting a 50% discount brings the price down to 1.75 cents per Starpoint.

Starwood Preferred Guest and Virgin America Elevate are ending their partnership on January 6, 2017, making that the last day that you can transfer SPG points to Virgin America Points.
Why does this matter?
In April of this year, Starwood Preferred Guest added Virgin America Elevate as a 1:1 transfer partner.

Through November 31, 2016, United MileagePlus is offering a transfer bonus when you move points over from a hotel loyalty program.

Transfer from most chain hotels earn a 25% bonus
Transfers from Club Carlson earn a 40% bonus
Transfers from Choice Privileges earn a 50% bonus

Since Marriott bought Starwood, one of the benefits the company has announced to members of both loyalty programs is the ability to transfer reward points between accounts.

Most airline miles charge exorbitant fees to transfer miles from one person's account to another's. For instance, United is currently charging $82.50 to transfer 5,000 miles from one account to another, which is more than the 5,000 United miles are even worth!

However, SPG Starpoints can be freely transferred from one SPG account to another as long as both accounts have had the same address on file for 30 days.

Until July 5, 2016, you can transfer 20,000 Starpoints to 33,750 British Airways Avios. The normal rate is 20,000 points to 25,000 Avios, but Avios is running a 35% bonus on transferring hotel points.

The only hotel-point transfer option with a decent rate is Starpoints.

If you don't have Starpoints, you can buy them right now for 2.45 cents each. The best number to buy would be 20,000 for $490 to maximize this promotion, since Starwood gives a bonus for every 20,000 Starpoints transferred to airlines.

Until July 1, 2016, Starwoodis offering a 30% discount on the normal purchase price of SPG points.

Starpoints are normally sold in increments of 500 points for 3.5 cents per point. With 30% off, the price drops to 2.45 cents each.

The deal applies to all purchases of 5,000 points.

This is the second cheapest I’ve ever seen Starpoints sold, behind last month's 2.275 cents price that was only open to SPG credit card holders.

Until today (June 3, 2016), Starwood Preferred Guest personal or business credit cardholders can buy up to 30,000 Starpoints with up to a 35% discount on the normal purchase price.

You can earn 10,000 Starpoints per referral to the Starwood Preferred Guest Credit Card, up to 55,000 Starpoints per calendar year. That's double the normal Starpoints per referral (but the same annual cap.)

I value 10,000 Starpoints at $250 and 55,000 Starpoints at $1,375.
How does the referral bonus work?
Look for an email with the subject "Limited Time: Refer a Friend, Earn Double the Starpoints" and click the Refer Now button.

Until today (April 30, 2016), you can buy up to 30,000 Starpoints with up to a 25% discount on the normal purchase price.

Starpoints are normally sold in increments of 500 points for 3.5 cents per point.

Effective immediately, you can transfer SPG Starpoints to Virgin Elevate points at a 1:1 rate. Like all 1:1 partners of SPG, you get 5,000 bonus miles for every 20,000 points transferred, so 20,000 Starpoints equals 25,000 Virgin America points. This is 2-and-a-half times the Virgin America points that you get from competing transferable points.