Earlier in June Starwood had announced a sale offer where all SPG members who buy Starpoints through June 30, 2017 would receive a 35% off on purchase. In case you missed buying Starpoints last month SPG has extended the offer for another 2 weeks until July 14, 2017.
The 35% discount is also applicable on points that you may like to gift to other SPG members. You must purchase a minimum of 5,000 Starpoints to be eligible for the purchase reduction. A maximum of 30,000 Starpoints can be purchased every calendar year. This includes points self purchased and received as a gift from other members. Usually every Starpoint costs USD 0.035. Under this sale the price of every Starpoint will drop down to USD 0.028.
35% is usually the highest point purchase value that SPG offers, so if you are falling short of points it may be worth stacking up. Also now that SPG and Marriott Rewards are interoperable, you may want to consider this as a way of stacking Marriott Rewards points.
If you are wondering where can you redeem these Starpoints. Here are some great choices