There are many companies on the web offering appraisal services for domain names. Some, such as SwiftAppraisal.com (which is free) perform this function entirely through automated software that checks for certain features, such as the presence of hyphens, total length, or an estimation of the market size. Other sites charge between $10 to $35 for a personal appraisal, which may be more nuanced. The problem with this approach is that every sale of a domain name is completely unique, and ultimately the value of a domain name is worth whatever a buyer will pay for it.
In general, it is worthwhile to look at sales figures for other domains in the same category, but even a cursory glance will reveal that final prices vary widely even for similar names.
However, a general guideline does exist. The most valuable domain names are the .coms, followed by .net, .org and .biz. Single word websites sell for the most money, though not all single words will have the same high value. Concatenated phrases are slightly less valuable than single words, and hyphens decrease the value further. Short words and phrases are preferable.
Not all words have the same commercial...