It's hard (well, actually impossible) to automate domain name appraisal, there are too many factors involved, some of them will be always based on human decision. Maybe this comparison is too exaggerated, but I guess it would be impossible to create the automated appraisal of artworks as well
However, if Estibot tells you that your name is worth that much or that low, it might be just an additional signal for you to take a closer look at why it could decide so.
It is commonly believed that a good approach for appraising your domain is to find some earlier reported similar sales. But you should also take in account when those sales were reported, how hot is that market (was it a single occasional sale or there's a steady demand for such names), and is your name really of comparable quality. The best places for this are namebio.com and dnsaleprice.com. And, reading DNJournal weekly reports helps with being up-to-date with recent sales and getting the feeling of what this or that type of name could be worth in the current conditions.