Hobbies is my favorite topic! Whenever someone asks about hobbies, this post comes to mind:
http://www.artofmanliness.com/2016/01/25/the-ultimate-list-of-hobbies-for-men-75-ideas-for-your-free-time/I have TONS of hobbies. Including: Music, Amateur Radio, Model Airplanes (the cheap electric+foamboard kind; google it), finance & spreadsheets, electronics, bicycling, MOTOR bicycling, working on my car, the list goes on.
I noticed at one point that some hobbies are especially cheap. For example, practicing that instrument you
already have but never got around to is great, and won't cost you a dime. Reading is much the same. Learning to cook awesome meals within with your grocery budget. That's cool too.
I try to avoid the expensive hobbies. Some hobbies however, have a small to medium cost, but have AWESOME satisfaction, and feel like expensive hobbies. These are the types I want to do more of when I reach FI. For example:
Motorcycles are expensive and somewhat dangerous, but
motorized bicycles can be dirt cheap (eBay and china stuff!!) and just about as much fun, more unique, and you don't go as fast, so less danger.
Model Airplanes used to be delicate, expensive, messy, gas-powered screaming machines in the air. BUT NOW, you can get EVERYTHING you need for like $200 bucks, and build your own plane in a couple days and learn to fly in a week, if you crash, pick up your electric motor and lithium battery, and BUILD ANOTHER IN A DAY. SO MUCH FUN.
Amateur radio can be expensive too, (towers, antennas, fancypants radios) OR I bought a kit made from discrete transistors on eBay from India for $80 bucks, made an antenna from wire scraps I found in a dumpster, and made contacts ACROSS THE US!
My point is, do the free hobbies, then after you have a little more to go around, do other hobbies in a very resourceful way. It's infinitely more fulfilling to do a hobby and be financially badass at the same time.