Caffeine Solution 5% + egcg from Deciem? Less than 10 USD to my understanding and the ingredients are pretty good. Two or three which of I'm not so crazy about, but overall worth of a shot. I bought it but I haven't had a solid course with it yet to really rave about results.
Overall, dark eyecontours, it's tricky ... I've had such from a younger age already. Good balanced meals, supplementation wise Zinc is pretty decent for many things.
Of course make-up can help, light pens and such, but those must be used with care (as make-up can also make you look worse) and it's only cosmetic.
Cold spoon or water / tea bags under the eyes are supposed to speed up bloodflow in a certain way. Or more so perhaps dilate if that's more correct, making the darkness and puffiness less.
And of course sleep is one thing, sometimes the darkness is from not sleeping well enough, but other times it can be a vitamin defiency. C and D can be taken into consideration supplementation wise.
Just something from the top of my head, world is full of possibilities and if I made blatant errors, someone can correct me.