If you really don't want it, return it and explain to your wife that it isn't her fault that the lens was listed in the wrong place. At least give her a lot of credit for knowing to look in the macro section.
If you want to focus to 6", you would need a Nikon 40mm or 60mm micro (or the equivalent 3rd party macro lens). The 85mm f/3.5 DX micro will also work well with your camera, but the minimum focusing distance is 10.8".
Extension tubes would allow you to focus closer, just be aware that auto-focus will no longer effectively work, and your depth of field will be very shallow. For an 85mm lens you probably would want a full set of tubes.A set of Kenko tubes at B&H is $199.