As a musician, you need a good source of supply for instruments, strings, accessories like tuners, metronomes, note stands, etc… most things can be ordered online, of course, but I personally love to go to a ‘real’ shop to make the right choice, get personal advice and have a good chat with like-minded people dedicated to what they do. Tom van Berkel is a great example for such dedication: you can usually find him in the basement of his shop doing repair work for all types of instruments. 50 years of experience make him the right guy to ask any question about your (acoustic) instrument. Stepping into the shop feels like travelling in time: the business started in 1676 in this same building which makes it by far the oldest music store in the Netherlands.
So far, I have never had repair work done by Tom himself, but he gave me very good advice by passing me through to a colleague of his.