I bought eyeliner. =O
Years ago, a family friend was offering glamour shots to everybody's daughter at a discounted price. It was one of those Taiwan-style photography deals where they provide some outfits, but you can also bring your own. They do your hair and makeup. They drive you around to parks and other public places to do exterior shots.
They give you an artisan album with all your pics in a hip magazine-like layout with hilarious Engrishy poems and quotes. They do a few enlargements, they give you all the proofs and the negatives.
When I went in for my photo session, I liked what the makeup lady did with my eyes. She just did one thin black solid line close to the edge of my lids and that's it. Well, she added some colouring and enormous fake eyelashes too, but I loved how the eyeliner really picked up my eyes and opened them up so much. I could be imagining this, but I also think it gives me a wider range of expression.
I started doing this myself afterwards. I use L'Oréal Intensifique liquid liner. A 1.5ml stick lasts me about 8 months or so. It's a pretty good deal for (CDN)$10-11 and everyday wear. It's better than the $10/month I was paying for a pencil liner that kept smearing.
I don't think it's entirely waterproof, but after it dries, I can run my finger over it and nothing happens. And crying, as I did at my Husband's Grandmother's funeral, didn't mess it up.
The downside to it is, well, it's liquid liner. The line has to be done in one stroke from the inner corner to the outer corner of the eye or it's screwed. You can't go back and forth like a pencil liner. Traditional drafting/lettering and Chinese calligraphy skills have done me really well, but I've learned to cheat a little too. I can fix minor derailments and small boo-boos. But generally, if you screw up, that's it, you need to wash it all off and start over.
Do you KNOW what a pain in the ass it is to wash makeup off ONE eye only? =P The worst is getting ready for some formal event where you get all the warpaint piled onto your face JUST SO and you screw up the second eye.