"$15 for $40 to Spend on First Order from Google Express"
 

First thing you should do is enter your zip code on Google Express and see what's available for your zip code.

https://www.google.com/express/

Here's the sale:

https://www.groupon.com/deals/google-express-nat-42

It's also suggested to read Groupon's refund policy, just in case.
Hope this helps.