How much should i sell my nikon d80 for?

It is about 3 years old. GREAT condition, 2 batteries, Nikon camera case, all the original boxes and cords (cords have not been used).It has a 18-135mm Lens with lens cap and filter. All manuals are included as well.

Look up ebay, amazon and craigslist. Search for cameras just like yours, then you'll know what the market can and will support.