Get 10% off on the US PlayStation Store by using the following coupon code:
The coupon expires the 01/12/2015 at 10 pm SAST. One-time use only.
Update: The US PlayStation Store will be holding a Black Friday Sale this weekend. So it would be wise to hold on to the coupon until then.
To access the US web store you need to be signed out of your SA account, otherwise it will redirect you. You can loads funds onto your US PSN account by buying vouchers from Amazon.