He says the new shareholdings are personal and have no link with Briscoe Group, the NZX-listed operator of Briscoes, Rebel Sport and Living & Giving.
"It just seemed like an interesting investment," says Duke, who wouldn't reveal how much he'd invested into the two businesses.
Price Wise operates two outlets in Ponsonby and Botany, as well as an online store, and is apparently on the cusp of an expansion phase.
That growth push is likely to be aided by having one of New Zealand's most canny retailers, Duke, on board as a shareholder.
North Shore-based BDM Grange was founded 25 years ago and is New Zealand's largest distributor of beauty and personal care products, according to its website.
Meanwhile, Duke says Briscoe Group, which was sitting on a $60.2 million cash pile at the end of July, remains on the lookout for potential acquisitions. He's not naming any names, but is happy to outline the retail segments the company isn't interested in - food, big ticket electronics, books and pre-recorded music. And Duke, who owns 10 per cent of Pumpkin Patch, still doesn't want to comment on those rumours about him upping his stake in the children's clothing business.
"I just don't want to find myself in a situation where I'm confirming or denying." Briscoe Group shares, which have gained almost 20 per cent over the past year, closed unchanged yesterday at $2.98.