In my opinion it’s a mistake to buy (or attempt to sell) a domain name based on an automated appraisal. You’re better off taking a look at sales history, paying close attention to what is selling/trending now vs in the past. Estibot might tell you based on their algorithm that Example.com is worth $xx,xxx because 7 years ago a similar domain sold for that price. Same thing with GoDaddy’s domain value tool. But they don’t tell you the circumstances of that sale. Also, the market might have changed since then. What was trendy in 2013 might not be trendy today.
Instead of automated appraisals, you should utilize a site such as Namebio. Do your own research and come to your own conclusions as far as resale value. And keep in mind that if you’re looking for your domain to sell in a reasonable amount of time, say months, rather than years, you should price it accordingly. But we’re getting slightly off topic here. We’ll discuss pricing and sales strategies in a future post. So, to sum it up: do your own research.