I would also suggest if you re-up your F/S thread after 7 days...delete the original. It slows things down and takes up space. No need to see 2 ads of the same basic post if you do a search for a specific item #.
Also, as was suggested..if you lower prices or change something update the title. A prospective buyer might not look at your add again if they think you re-upped without lowering the price. I think this one would help sell lots more trains!