The higher end bikes tend to sit for longer as the market for them is smaller but I feel there is a lot more value to be had for $700 than for $400.
In the $300 to $400 range you have tons of ****ty bikes being sold by people who are basically hoping to find a buyer who is ignorant and won't know they are getting ripped off---you at least have had the common sense to do a bit of research, many people do not.
In the $700 to $1200 range you are more likely to get a quality bike and the seller is likely going to be someone who knows what they have and are interested in bikes in general. That usually means the seller has taken care of the bike or has had it tuned up over the years.
Of course, there are outliers in both ranges, people who think their bike is valuable just because it is old and people who have a 1968 Cinelli that grandpa rode and figure it is worth about $100 because gramps was a cheap bastard
