Because the expensive hobbies thread is depressing me.
What are the hobbies you participate that almost anyone could get involved in, for minimum cash? They can have the potential to be expensive, but you should be able to participate at least at a basic level for pretty cheap.
Yo-yo: I was really into this about 6 years ago, I could probably have competed (didn't have the confidence at the time), I practiced for several hours a day. I saved my money for about 2 months, and bought a high-end yo-yo. It was sweet. I also had a bunch of other ones, specialty, or ones I could bring to school and mess with. Entry fee: $12 for a fireball, a pretty decent yo-yo.
Small electronics: I repaired/built a bunch of tools for my dad as a kid, and nowadays I do some computer case modding, and appliance repair. Entry fee: $9 for a 20w soldering iron, $2 for solder, and all the junk you can get your hands on, I never paid for any of my electronics. Dumpsters and side-of-the-road specials.
Running: $30 pair of sneakers, and pavement. Go.