Buying and selling domains is a popular way to make money in the Internet.
Prices of domains can fluctuate and ir really depends on who wants the domain and especially on how much they are personally willing to pay.Domain names that have been established or with content can be worth a lot of money.

It is like with collectibles in the respect that if you do not have the right buyer then the domain is really worthless, is this correct? How would you really know it might be worth something.

domains are like property..only difference being that they are on the Internet..you buy them for less and sell them for more just the way you sell any other property..however, the only difference is that in case of domain names, there is no way of knowing for certain what price a domain can be sold for..