Plate spinning,staring at cars passing by (that's pretty popular here in Texas for some reason), throwing darts, coming up with water/generic soda-based drinking games, power-walking, funky walking (like power-walking but performed by increasing one's funk levels rather than power-levels), jive talking (there are plenty of low-cost slang guides in books stores across America...what book stores still exist,anyway), learning new languages (why stop at jive when you could strive for more? Again, there are affordable translation guides and educational books out there.), becoming an amateur historian (by raiding as many brick-and-mortar libraries as you can), learning a cheap instrument (harmonica or kazoo?) or the latest dances (or some ancient dances that few even remember any longer. How about that Fox Trot?) are some non-electronic hobbies to start for under $100 that no one else mentioned yet.
Whether they are any good or not are up to you.