Domain Appraisal Sites..Are they Reliable..?

I checked my domain ukgbp.com on various domain appraisal sites. They all gave different value from $10 to $1200. I want to know how it works and Are they reliable. They are almost correct on traffic that is more than 3,20,000 / month. But CPC is again different from $0.10 to $0.70. As it is short and meaningful name. UK stands for United Kingdom and GBP stands for Great Britain Pound. So UkGBP could be very best brand for any Financial Banking sector company in United Kingdom. So when to sell what we should consider as realistic value of any domain. As I place make offer $990 at Sedo. As they sites cannot able to apprise Brand Value of domain. Want to know how reliable these domain appraisal sites..? As one website gives me $10 value and I paid more than that for domain registration.

What is CPC. Its Cost per Click .. But what is that..?

Thanks in Advance

 

If you search for automatic appraisals in this forum you'll find many threads which say the same thing, ie. that auto appraisals are completely wrong and useless.

regarding cpc,
I believe you'll find more and better info by googling it.