The following is a Question and Answer with a DotWeekly.com reader.
Q: Wondering if you have ever paid more for a domain name than it’s valuation on Estibot.com or other "valuation" services?
A: The short answer would be Yes and No. You really should not put much, if any trust in domain valuation services to the real amount paid for a domain. I only answered yes, because most are always wrong (high and low) and I answered NO, because most are always very high.
In-depth Answer: I really would not base any domain name on the value given by a service, Paid or Free. Since metrics are often used to give the estimated value, doesn’t always mean the metrics are right. If it’s done by a human, that’s what They think the value is, which doesn’t always mean They would pay the given amount.
One of the biggest things that I see wrong with metrics used in valuing a domain name is Overture / Wordtracker data. Even Google search volume is questionable directly from Google itself. Since plural and singular variables can be very wrong, old data, or the term may be "included" in a search string etc. "Search Volumes" are often a metric that will greatly increase the "dollar value" of the domain provided by the service.
Do these "search volume" numbers really mean you will get that kind of traffic to equal the metrics value? Highly unlikely!
I really base the value of any domain purchase I make off my Gut. I ask myself several questions about the domain.
1.) Is it highly likely that somebody would pay more then what I am purchasing it for? If yes, it’s likely a good investment.
2.) Could I turn a profit on the domain TODAY if I wanted? Even $10. If yes, it’s a fair investment with limited risk.
3.) Am I the only one that would want this domain? (Google should be able to help you answer this.) High Exact returns, should reveal others would be interested.
4.) What have similar domain names sold for? (NameBio.com) and where did they sell? Sedo / Afternic is more like to be an end user sale. Even NameJet get’s UP There in price. SnapNames can be getting higher in value, but can be a better base line for wholesale. TDNAM is even more likely a wholesale market price.
Paid and Free appraisal services for domain names should be a simple guide. I personally would not use one to determine the value I sell or purchase a domain name for.
Having a close friend that knows domain names and can provide unbiased advice is something that can greatly assist you and be a nice thing to "make sure". There is also KeyFactor.com 
Me.
Me.I have seen Estibot.com, LeapFish etc give what I would consider pretty close valuation, undervalued and extremely overvalued. Since it is pretty inconsistent, one should really put little to no trust for exact or even near value on the domain to guage "value".
You will be the deciding factor in the value of the domain name. If you are willing to pay $xxx for it, then that is your value. You really have to go with your gut and what you are willing to spend or sell at. If you are happy, then it meets your value.
