I personally think splurging should be left for products that go directly on the face, unless of course you're someone with problem skin. I had acne and oily skin so I understand that when it comes to makeup, the best products often require splurging.
That said, I prefer to splurge on mascara and save on eye liner.
i have tried E.L.Fs liquid eyeline and its great it (cost like 2 bucks) but my favorite is the body shops liquid eyeliner (costs like 15 buck) cause its a little easier to apply then E.L.Fs. I like them cause they give intense color, doesn't smudge and dries quickly. And non of them are tested on animals which is great :D
Save, save, save! N.Y.C makes amazing felt tip liquid eyeliners. My favorite is the High Definition liquid liner I got for under 4$CAD at WalMart. I have oily eyelids and I NEVER have to touch up or worry about it smudging. This stuff if bomb!
save, there are so many good liners out there that are cheap. I love prestige total intensity, it is a creamy pencil that looks more like liquid because it is very pigmented and bold. that is sold at ulta and drugstores.