Just found this mail from Medicine Flower in my inbox:
“We are celebrating St. Patrick’s Day in style with 17% off of EVERYTHING!
Use code “gogreen”
Going on now until March 19th”
the same mail has the code as GOGREEN, elsewhere so I guess you can type it either way.
EDIT: here’s a link to their flavour page:
http://www.medicineflower.com/flavorextracts.html
Can’t see any mention of the discount on their website, so it’s perhaps specifically aimed at subscribers; which is not to say it won’t work for anybody else 