eBay completed auctions is used by most estate and smart garage sale folks and is used as the highest price to be expected. It represents, in most cases, competitive bid prices (it includes Buy it Now sales too) and most local sales at train shows, estate sales etc. are not comparatively bid on and to sell, the price has to be lower than the eBay completed auction price.
eBay completed auction prices, available in moment on a smart phone, has obsoleted those old Lionel Price Guides we all used to determine prices for used trains. There is no need for price guide books that would be out of date the day published.
Charlie