If you want this site to come back, then what are you waiting for to add this? Is it really that difficult or consuming to add a buy/sell section?
I can think of 6 different sites that are similar. Three of them I only go to, to check out the for sale listings.
What will help the for sale section specifically to gain traffic, and get people interested in coming back, are: two SPOTTERS THREADS: PARTS & VEHICLES. Even if WE don't have enough to keep it going, we get to contribute, help each other, and still look for and find the only dedicated NBS spot ANYWHERE for parts. Its lets US use THEM, to get a reason to create activity. Some of the other sites have them, but being a NBS specific we could be a little more open about finding unique, outdated, or quality stuff. This would also apply if you included a WTB section.
In a perfect world, a cool feature would even be able to do something like a Google maps, where we could tag with a keyword the parts we are selling and location. (Completely unnecessary now, but) if you actually rebuild this site it would give people a chance to quickly check for parts, and gives them a reason to return.
I think, it's not that we don't need a for sale section because we don't have enough traffic. We need one to create the traffic.
I didn't mean to be rude if that's how it sounded, that's just the way I am. For me, I think it's more respectful to be honest with people, then it is to tell them what they want to hear, (for both of us). At this point in my life, I just keep it blunt. Just trying to help with a "complete point".