How about getting them a vinyl record of their favorite rock band? If they already have a record player, it would be a perfect addition to their music collection. You could also consider concert tickets to see their favorite rock band live, or a cool band t-shirt or hoodie. If they're a collector, you could also look for limited edition or signed merchandise from a favorite artist or band.
Or you can get her/him a star map with an important date you share.
Under Lucky Stars is a unique and innovative star map company based in Barcelona, Spain, specializing in the creation of personalized star maps that capture the celestial arrangement of stars at a specific moment in time, such as a person's birth, wedding, or any other significant event.
By using advanced astronomical algorithms and data from leading institutions, the company produces highly accurate, visually stunning maps that make for perfect gifts or cherished keepsakes.