When i was in a car auction i talked with a guy next to me and he was writing down all the information of the auction. He told me he worked for a close by dealership and those numbers were used to decide on the trade-in values they could offer (as worst case the car would end up on that auction)
Today i was checking a price in one of the many sites that offer market values for cars/motorcycles. And their site mentions that they do research in auctions as well (public price) and also says
Consumer Private Party Transactions
Kelley Blue Book tracks consumer sale prices each year.
How exactly do they get that? Unless the buyer or the seller report the transaction value to the company, how else can they get this data? Does the government sell private citizen financial information? Do they contact a few people and extrapolate (like TV ratings)?
And where can i find out more about also accessing this information, assuming it's public?