I suggest going to Gun Broker, & doing an advance search for "completed auctions". That's guns that actually sold, rather than just asking prices. Of course thee will be some that might have sold for an uncharacteristically high, or low price, but a quick average of the in-between ones usually indicates value or what byers are currently willing to pay these days.
Most of the SS 45 Bisleys seen there will be the later Williams version, but I know no reason that an Accusport, Williams or other dist. version of the same gun would be priced differently.
The Turnbull Bisley would be tempting ( see it has been relisted) ... but not at that price. I see a 5 1/2" SS ROA there for $1895.... Crazy. I paid $800 for mine and thought it was expensive . That wasn't that long ago either. Glad I am not in the market for anything right now.
It's kind of pointless to go to Gunbroker to get prices for any gun, unless that's how you plan on selling it, and giving up a percentage when you sell it, and then they add tax, and all the other hoops you have to jump through. Truth is, those big auctions work off the premise that it only takes 2 people in the whole country that makes an auction. You still don't know how many times you will have to run it through to sell, and you have no idea what you are going to get it for. I've done this before two identical guns. One went for a really good price so I decided to sell my other gun and it didn't get nearly what the other one did.