Are you planning to attend a birthday, thinking of buying something that will be of use the birthday celebrant? If so, then you should consider the things that the celebrant wants to do during his/her free time.
If the celebrant is a trumpet player and own one then I would say an excellent trumpet gig bag is a perfect gift. It will be very useful especially if the celebrant is traveling from one place to another to perform.
I am certain you will find music store online that offer good quality of this kind of bag.