This is a knife that cuts both ways, and I don't know how you fight it. Dealers put guns on auction sites at sucker-fisherman prices. Then they are usually relisted for months or even years. I wish these sites had a search function to filter out guns which have been re-listed over and over. It just clutters things up and wastes our time. As you say, it also confuses folks who are trying to get a handle on what their gun is worth.
But we see the exact same thing at gun shows and shops. If a dealer has a brown roach, he prices it at 110% BlueBook and claims it is pristine. If he's trying to buy your gun, he will magnify every flaw and tell you your Gradfather's Parker is worth little because they're not making parts for them anymore. This is not unique to Lefevers. For every gun that has a Buy it Now price which is set too low, there are 10,000 which have insane reserve prices or starting bids.
I always tell folks who want an honest appraisal to watch the same guns in the same condition for a few months on the larger nationwide auction sites, and take an average of ACTUAL SALES PRICES. Nothing else matters.