Hello, Stephen, and welcome to our forum!
The short answer, unfortunately, is that these wines are probably too old to be drinkable or to have any value. This is almost certainly true of your 1926 wine, a Beaujolais that should have been consumed within five years or so of its production.
The Chateau de Ferrand is a finer wine, a St.-Emilion Bordeaux, from a fine vintage, but again, a 61-year-old St.-Emilion is rather iffy.
And finally, Grand Puy Ducasse is also a well-regarded Bordeaux, a "fifth-growth," but even so, at 31 years its chances of survival aren't great. Much would depend on its storage conditions, but as a general rule, a wine of this type would need to have been kept on its side in a wine cellar at a constant 55F to have much hope of still being good.
To answer your more basic question, an excellent resource for seeking current retail and/or auction prices for collectible wines is Wine-Searcher.com
, which allows you to search its database for wine names and vintages and returns links to commercial vendors who carry those wines, with current prices.
Wine-Searcher does have one U.S. listing for 1975 Grand Puy Ducasse, at $55 from a New York City wine shop that I might not recommend for reliability or price. It shows various listings for older Chateau Ferrand, but no 1945s.