How much should I sell this lens for?

It's a AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6G ED II, still in original packaging.

Even if it is in its original packaging it's still consider pre-owned. If the lens, like the Canon 18-55, retails for around $150, I'd ask about $90 for it and stress that its never been out of its original packaging.

Also check ebay for what others may be asking.