Camilla bought the bargain, which celebrated the Queen’s 1977 milestone, for £1.50.
She spotted the commemorative mug while in Mossley, Ashton-under-Lyne, as she visited Emmaus UK – a social enterprise community which supports homeless people through education, training and personal development – on Tuesday.
The royal visitor remarked: “I see you’ve got a nice jubilee mug. I am going to buy that. I have a whole collection, believe it or not.”
Touring the shop, the duchess said: “Ooh there’s a really nice teapot here for anyone who collects them. I wish I had a bit more time here.
“It’s a great place to get presents if you have the time.”
Camilla said there were “plenty of bargains”, adding: ‘You’ve even got a wedding dress.”
The duchess was attending a pre-Platinum Jubilee Big Lunch with supporters of the annual community get-together, which this year forms part of the official celebrations in June for the monarch’s seven decades on the throne.
Camilla, who is patron of both Emmaus UK and The Big Lunch, was joined by Platinum Champion nominees at Emmaus Mossley.
Performers from Global Grooves, who are taking part in a Jubilee pageant in London on June 5, greeted the duchess, who gave a broad smile as she shook hands with Padmini – a giant, 14-foot high puppet.
Camilla said: “What a lovely place this is and what a fantastic view.”
Inside she toured the Emmaus workshop and met volunteers who were upcycling and reupholstering donated chairs in preparation for the charity’s Jubilee events.
She chatted to George Hall, from Mossley, who told her he would be 75 in May, about her own up and coming 75th birthday in July, saying: “Two months earlier than me. The trouble is that you just don’t feel it, do you?”
Cutting a cake to mark the occasion and celebrate 15 years of Emmaus Mossley, the duchess told guests: “I am thrilled to get everybody here today to celebrate the jubilee weekend, when I hope you will be having an even bigger lunch on the day.
“The aim is 10 million people, that’s what we are hoping. It’s a lovely way to celebrate. It’s a lovely way to get to know your neighbours and to have a lot of delicious food and chat.”