I have a thing about eyes, in Second Life. Eyes are often the difference between an avatar that looks like a person, and one that resembles a department-store mannequin or a cartoon character on Ritalin. Cheap, low-quality eyes can make an otherwise-attractive AV look cartoonish and goofy, which can be distracting and immersion-breaking.
High-quality eyes are available inexpensively from merchants like Ikon and Mayfly. Browse, try demos, find something you like, and then spend a few Lindens. You'll only ever have to do it once, and you'll be glad you did.