This assumes that pipes have a static intrinsic value. But, really, you're only going to get what someone is willing to pay, and that can change from day to day, or even what platform you are trying to reach out to buyers on. It's not like gold, where you can track market values set on how much investors are paying day by day. Nor is there a Bluebook, which right now isn't worth crap, because used cars are selling for more than new ones at the moment.
So, having someone tell you value is going to be a waste of time. If They say a Dunhill is worth $250, then if they try to ebay it themselves, they most likely will never get that price. However, if they used a seller like Pipestud, they might get that, or even more, depending on how many Dunhill collectors are bidding.