Prices seem to differ widely based on what region of the country you are in. Others have recommended that the best way to see what is a good price for your area would be to get quotes from many different dealers in your state. You may even consider going to a different state to save on taxes.
The number of hours the tractor has on it will have some bearing on the value. Price a new model with the same appointments and you will have a fair idea of how good a deal it is, or is not.