How do people get materials for Chemistry or projects? Ebay?

I've been wondering about this ever since high-school, but where do people buy these random chemical compounds to do experiments in their back yard? Like copper sulfate among other things.

I understand teachers probably get them from a school approved source, but a normal person just trying to get small things like smelling salts or dry ice is apparently a huge hassle?

Im not actually trying to get anything, my mind is just blown that people can just randomly get odd, dangerous chemicals from seemingly nowhere