All depends on where you live. A buddy of mine just sold a black 06 limited for 4400 that was all stock and in nice shape. (Pa)
Does the quad your looking at have a title? If so, id say 3k is fair if its in good to excellent shape. But hell, if he will go for 2600 thats even better.
Remember, most of the time its not what the object is worth.... Its what the buyer is willing to pay.
Post some pics.