As others have said, for the first year or so expensive balls are a waste of money, there will be a fair few that disappear into the trees never to be seen again on their very first hit.
Rangefinders or GPs stuff will be out of budget
If he hasn’t had any lessons then maybe get a couple of 45 min lessons for him to accelerate his progress.
If he is going to the range over winter then a gift card for range balls is a very practical, boring, saving him some money type gift.
If it was me then the gift I would be happiest with in that price range would be the green fee for a round at a decent local course. I play at the cheap course where I am a member, or at other places in the £20-30 bracket, so hitting somewhere that’s a bit nicer would be a real treat, but you’ll need to make sure he has someone else to go with as it’s not something he is likely to want to do on his own.