Starbucks is selling $20 eGift cards for $10 if you buy them using Visa Checkout instead of credit card directly. If you can still buy a gift card at the link, the promotion is should still be alive. I just did it on 5/11/16 at 3:40pm Pacific and it worked for me. Otherwise ends 5/17/16. See terms:
Be one of the first 325,000 to buy a Starbucks eGift Card (min $10) using Visa Checkout between 5/3/16 – 5/17/16 and we will add an additional $10, courtesy of Visa Checkout. Send $10 – they get $20, send $20 – they get $30, just for using Visa Checkout.
The bonus wont be reflected in your checkout experience but will be confirmed in your email receipt. Limit one per person. See Terms and Conditions.
Note: Technically, you should buy a $10 gift card for $10 and they’ll actually send a $20 one… I know, confusing.