The 69-year-old, from Rugby, was familiar to viewers as a stalwart of Antiques Road Trip, Bargain Hunt and Flog It!, making hundreds of appearances over 12 years.
Nick Hall, of Frank Marshall in Knutsford, Cheshire, said: "I was very sad to hear of the passing of David Barby, not only a great wealth of knowledge and ambassador for our trade but a lovely gentle man.
"I have spent many an hour chatting with David over a good meal and a glass or two while away filming Bargain Hunt and Flog It! and, like all the other experts that have spent time with him, found his company always a great pleasure. In fact, I did my first Bargain Hunt with David and he made the whole nerve-racking experience a pleasant joy. A tragic loss."
Auctioneer Charles Hanson told the BBC he was a "great friend" and said "no other expert... could rival his great human touch".
"He built up the great passion the public had for these programmes," he added. "More importantly, he was a man of the people. Anybody could speak to him and he had time for so many members of the public to share their stories, memories, nostalgia and passion for old things."