Long time lurker, so please feel free to correct any mistakes :)
This seems to be a good price for the well-renowned Nitecore Tube keychain light.
No coupon required.
This deal will likely expire at the end of Banggood's 10th anniversary sale (so around noon tomorrow if my calculations are correct).
http://flashlight.nitecore.com/product/tube for specs.
I have one of these and it is amazing bright for its size and price.
EDIT: Green seems to be the only colour currently in stock, others will be shipped out after the 15th (restock).