Quantum optics experiments are probably the most accessible for garage hobbyists but it’s still a ~$k hobby once you start buying lasers, electronics and optics.
I remember a very simple experimental setup we did at my initial physics class, my university at the time was in construction (we didn't have equipped labs), with a result similar to the two slit experiment by shining a cheap laser at an angle on a cd/dvd. Something like this: https://www.reddit.com/r/Physics/comments/paqnya/doubleslit_...