Domain names are very illiquid and there are lots of different ways to define worth. On the low end, there is this price: how much could I sell it for tomorrow in a no-reserve auction? On the high end, there is this price: how much could I sell it for if I spend a year cold calling and negotiating with potential end users?
Almost any domainer will tell you to completely ignore automated appraisal services like Estibot. Most will also tell you to ignore professional appraisals; they are better at estimating auctions prices than anything else.
