I've had a but of feedback already from the Golf Collectors.
Apparently you'll maximise your sale value if you split the balls up and sell individually, maybe £30 to £50 per unwrapped ball and £40 for the box.
Always seems a shame to me to do this but if you're looking to make the most money then it would be the way to go.
Here's a website listing prices for wrapped golf balls.
I had one message from someone who says they'd be interested in buying the lot, if your friend is interested you could pm me their email address and I can forward this on to the interested buyer and they can discuss price between them.
Alternatively he could email directly to:
