This business is definately divided into seperate 'niches'. The problem that faces the domainer is identifying the 'niche' that s/he is selling to.
It is obvious that 'end-users' are the preverbial 'pot of gold' buyers as far as we domainers are concerned, in general they pay the most for a domain name. However it should also be recognised that some domain names have an inherent value due to natural traffic that to a 'domain parker' makes it valuable, sometimes this value can far exceed the value an 'end-user' would put on a domain, here the most obvious example is Sex.com.
To confuse matters further we now have a plethora of domain suffixes (gTLD's and ccTLD's), some domain names are percieved as having a value no matter what the domain suffix is, to date this has mainly been seen by domainers, even though there is no natural market (or extremely small market) for the domain in the suffixes geographic location. A good example of this is of course Poker.??.
As domainers we use different tools to identify the possible value of a domain, Google count and Overture count being the two most prominent. The Google count shows the number of pages associted with the search term, usually in the multy-millions and the Overture count gives the number of times a term was searched for on the internet in the previous calender month, the higher the Overture the higher the percieved value of the domain name.
Just so as not to make things too easy in finding a domain name that may be of value we then have IDN's. These domain names use 'local' alphabet (non A-Z letters) and the domain names are targeted towards a specific written language. Some of these command very high prices, mainly depending on the language and the type-in traffic they recieve.
All of this then leaves us as domainers with a problem, how are we meant to understand the business? All we do is either to try and track the market and hope we react quickly enough so as to profit from it, or seek out areas that as domainers we see as a future market and invest in that. In the meantime big money has moved in and we as individual domainers are constantly being sidelined in the market.
This is a great business to be in that I love, and I am sure most of you feel the same, but again please don't ask me to understand it!