What's the point in it, for a while now I've replied to threads, with good intentions of purchasing or showing an initial interest.
Then you find no one replies, then things vanish, or sell to someone several responses later....

No email just asking are you still interested as you replied first?

Really frustrating....

Can i have first dibs with a reply to this?
Will have to get back to you as i haven't figured out what to say yet.

Hasn't happened to me often and I buy a lot of stuff I don't really need but a couple of times recently I've thought I had an agreed deal to be told later that someone offered more, but if you've agreed then its agreed?

Its quite a difficult thing to be totally fair when selling but having bought and sold loads of things on forums I can only recall one time when it got a little shirty. Normally a pm or a reply on thread with a "I'll have it, paypal address pls" normally secures the sale. If someone asks a question then a definite buy comes in after then that trumps the question. If I really want something then I'll send a pm and reply on thread pm sent. If i'm not sure of fitment then i'll just reply on thread the question and if I lose out no hard feelings.