I dont think it's fair to say because you want something like that, it has to happen, and you're going to write up the rules. Jumping the gun perhaps? How about a vote?
It isn't more work for the Mods. That is one of the reasons I've offered to help, so that there doesn't need to be any more work for the Mods. Doesn't hurt to give a little back to the forums, especially as I've already done the majority of the work already elsewhere on the internet. The only thing the Mods would have to do would be pin a topic, add the rules and change the settings on the forum so that Users can make posts but not reply. If you think that's too much work for them, then what are they here for eh?
I'd be more than happy for it to go to a vote, but to be honest, I think the Mods should decide.
I personally prefer it the way it is. That way if someone posts a request, and someone's attempting to rip them off, folks can tell them or point them towards someone cheaper. And TBH, it would only make it easier for folks to charge people much more than things are worth - without anyone being able to say "Hey, I dont think so!".
The way I see it, and the way it is in most other transactions other than online forums, is that
it is the responsibility of the buyer to decide whether or not they feel the item they are buying is good value.
Another good reason to not go ahead with your plan, is because it is less likely that someone will take time out to pm than they would to answer on there. Also, not only are the classifieds a useful place for buyers and sellers, but also for those also looking for the same things to read where to look and who to ask. If it were all conducted via pms, there'd be far more posts asking the same things purely because people couldn't see answers to other people's queries.
You'll see this is addressed; Sellers should be encouraged to post any queries, and their reply, in the original thread as an edit.
Plus it'd be an even higher workload for the mods. Methinks if sellers are concerned about folks piping up offering cheaper options, they shouldn't ask over the odds for things - if they dont have anything to hide, they are perfectly capable of defending themselves or choosing to advertise on the free ads or similar where replies are not possible.
But why should a seller ever have to defend the price they're offering? I saw (I think it was Rooster) post recently that if a user wanted to advertise a £10 note for £20 then they should be allowed to, it is the responsibility of the buyer to decide whether or not they're getting a good deal. If you've got the internet, you've got access to ebay, and how long does it take to check there and see if a similar product is for sale (or sold...) recently at a similar price? Or look online at other stores? It is the buyers responsibility, it is only online forums where people totally unrelated can chip in and say they don't think a price is fair. And why?
And I am in no way talking about Spooky here. There's been far worse prices posted on the boards than 50p higher than an Ebay seller LOL!
I never even saw Spooky's thread, I only found out there had been a recent issue after they posted in this thread. The fact that it happens so regularly is surely testament that perhaps it needs changing?