Remember, Macs hold their value a long time. I am sure someone here could make a simple program that could be updated via the net. Shoot I could make it in a few hours! The hard part will be getting the current market value and how far back you should go. The last 5 years or 10? Also, who is to say what the value is? I place great value on my Beige G3 but some people think it is worthless!