Well, there has been a lot of great responses here. Tons.
There are a few things id like to point out. This is my understanding. Blade forums is a place for knife enthusiasts and affectionados to talk about and learn about all aspects of knife collecting. It is not a internet store, therefore retail rules dont apply. Just because your first in line doesn't guarantee that you get to buy. The exchange was created to sell blades to other enthusiasts in order to downsize or to fund another purchase. Lots of the time these blades are sold at a very good deal!!
For instance...sometime buyers dont want the "public" to know they bought a particular knife. Other times a PM can be a "Ill take it" but i need clarification on some info not found in the sales thread. This for me, is a first in line. Even other times someone will post "Ill take it" and then ask a bunch of questions over PM and then back out.
As a private seller between other knife enthusiasts, i will always reserve the right to sell to who i wish to. That being said, if first buyers time stamp is cordial and prompt, they get the knife.
When it comes down to the nitty gritty, as others have said, friendships are formed on BF, and sometimes you just want a beloved knife to be bought by a friend who loves it, rather than someone you dont know. Like i said, its not a store.
Stores make money...usually BF members don't.
Just my thoughts.