I don't see an issue with this thread. It is harmless, unless folks choose to call out specific ads or post directly in FS threads, which is not so cool.
What I see are two distinct groups of users in the Classifieds. Group A are serial buyers/sellers and folks who are flipping gear for a profit. They are scanning ebay and other sites for good deals all the time, watching all the deal sites, etc. They know the price range for most common items, and will attempt to buy at the low end of that range and sell at the high end. Group B are the folks who only enter the buy/sell world when they actually want to buy or sell. They don't necessarily do a lot of homework, and don't want to spend a lot of time waiting to find the right deal. When they sell they tend to sometimes think about what they paid for their gear, not what price the market is supporting.
I'm generalizing, of course. Lots of folks don't obsess on used gear prices but still do enough research to price something accordingly. But I think the pricing gap the OP mentions lies somewhere between the two groups I am describing. No harm in that. As others have said, if a price is too high either ignore it or PM the seller offering what you think is reasonable.