Here's a bunch of free/inexpensive, fun hobbies you might enjoy (note that these hobbies are free or inexpensive until you go hard-core and start traveling the world for your hobby!):
- Pokemon Go.
- Bird watching.
- County collecting.
- Beach combing.
- Photography (with your smartphone, not with fancy cameras and lenses).
- Collecting flattened pennies.
- Letter boxing.
- Urban exploration.
You can pretty much make a hobby of anything you find fun and interesting and while some hobbies can cost a fortune (golf and diving come to mind), there are many free and inexpensive hobbies you can do for fun.