Well, it's $15 but it's the best pencil eyeliner I've ever used. It's Prescriptives Softening Eyeliner. It goes on great without tugging and comes off really easily too.
I think Maybelline makes a pretty good eyeliner too.
Mary Kay is good. I use that or I use Sonia Kashuk pencil eyeliner (from Target). I like the Mary Kay one because it's a twist up and seems to last longer. However, for pencil eyeliner, SK is the best I've used.