Even though the last novel in the Harry Potter series was published in 2007, the fever never really died down. There always seems to be something or other to reawaken diehard Potterheads.
A large array of gifts exist for Harry Potter fans. Wands are fun for the young ones and collectibles for the older. Costumes like cloaks and ties are fun too - although may short-lived and not very practical, unlike cups and mugs. Franchised products like Lego and Monopoly sets could provide hours of fun, and collectibles like Hermione's time turner and a quidditch set could last forever.
Bonus idea? A letter of accepantance to the Hogwarts School of Witchcraft and Wizardry! Anyone who has read the series has definitely dreamt of receiving that life-changing letter by owl post, even if they are well past their schooling years. You can even get a personalised version, making a low-cost yet thoughtful gift. And luckily there are many templates available online for you to do this for your Muggle-born.