We've had a major issue this year and someone we approached for help (and was expecting to pay thousands to) has gone above and beyond, for free, to get it sorted out for us. (Because he's a good guy, it was no fault of ours, and it was an interesting case for him to dig into).
We want to get him something for Christmas as a thank you but really struggling for ideas. He's very wealthy, doesnt need anything. Doesn't drink. Has three young kids so hobbies few and far between at the moment but plays guitar. Budget around £50ish.