In general, the shorter the domain name, the more it's worth. Shorter names are easier to remember, easier to type and more brandable. For example, MyRealtor.com is easier to remember and type than MississippiRealEstateCompany.com.
Similar to domain length, domain names with less words are usually more valuable. One word names are easier to remember, easier to type and more brandable than two or three word names. For example, Cars.com is more valuable than NewCars.com. NewCars.com is more valuable than BrandNewCars.com.
Like fine wine, domain names that have been around for a long time may be more valuable because they tend to rank higher in search engines. They also may have more established websites and the owners may want a higher price to be convinced to sell them.
Many internet users simply type what they're looking for into their internet browser address line. Domain names with more common words tend to draw more type in traffic than those with less common words. For example, Cars.com will generate more traffic than Baskets.com and, consequently, is more valuable.
Dot com was the original domain extension for commercial internet web sites. Big companies have invested billions of dollars in promoting their .com names. Consequently, for commercial internet web sites, .com is still king of the hill and and .com domains are more valuable than .net, .org, .co or any of the other extensions. For example, Cars.com is more valuable than Cars.net.
Just as the price of a home is based on sales of similar homes, domain names are also valued based on sales history. There are many web sites that track domain name sales such as www.dnjournal.com.
Domain names with existing visitors and revenue earnings don't require the same level of effort to develop and promote than domain names with no traffic. Consequently, these domains may have a higher value.
Hyphens and numbers are two other factors that affect domain pricing. Domains with hyphens are usually less valuable than those without. For example, SportsCars.com is more valuable than Sports-Cars.com. In addition, domains with numbers are usually less valuable than those without. For example, Cars.com is more valuable than Cars123.com.