No, it's nothing like that. Private sellers of boats like ours add a little negotiation room over a realistic price garnered from similar listings in their part of the country.
Brokers take at least 10 percent of the sale price, often with a minimum of 3K. The ask is therefore always higher than private.
Junk boats sell to newcomers because nobody else will touch them. Well maintained boats have a pretty obvious value to experienced sailors, who can compute at a glance work needed and work already done.
Yes, a broker can tell you what similar models sold for across the country. It's part of their service to customers. Asking prices are public, selling prices are not, as far as I know.