What is the best way to find the value of a domain? I have tried dnscoop.com and they give a value of my domain over $200
Don't do automated appraisals. Best way is to ask for an appraisal on the forum and get people who are educated in the domaining industry to place a value on your domain. You can also do a little searching around and try to see for yourself.
Automated appraisals are not always correct, infact they are not even close sometimes. Ask in forums, sometimes you do get differing opinions but they are much more accurate
I feel that sedo.com at least give you a rough guidance for your domain name price. From there you can more or less gauge it.
You're contradicting yourself I know you meant to say they "are always not correct". To find the value of your name, post it up for appraisals on this or other domain forums where you'll get a free appraisal from domainers in the business.
Estibot.com is good for rough appraisals, plus you'll receive lots of other info instantly such as Overture and Wordtracker results. If it's a long two word name such as IncompleteFractionals, which would be worth nothing btw lol, separate the two words with a hyphen like this: Incomplete-Fractionals. Make sure you put too the extension in the search box. Too the hyphen search will be a super critical evaluation. I know the chap who runs that service and speak with him daily, he's totally trustworthy and accomplished a great tool there for domainers. I do agree though that getting appraisals on forums from unbiased experienced domainers is the best way of getting one done accurately.