BZTTLG7D7 $ 10 for 6 months (from upsmychoicedeals.com)
BTH5ZYHD3 $ 3 for 3 months (from slickdeal post)
DONT FORGET TO CANCEL AUTO RENEW
I tried these coupon on UPS website, but all the coupons (no matter expired or not) were shown as "Missing or Invalid RequestType ". Then I tried the iOS app, it worked there.