I like your thinking!! I was hooked too the first time my brother showed me a video of one of these.I'm a hospital CEO with no actual skills, but a willingness to try anything (it's gotten me this far!). Now I have to start scavenging bikes and stuff, and laying out how I would make it work with my yard (I have lots of trees to navigate)
First thing I did was find a good motor. It’s the heart of the system and probably the most expensive. If I couldn’t find a motor then the project was done. I got mine at Frightprops. It’s a great motor - very strong and will allow me to expand in years to come. But there are a lot of videos on YouTube of people who are more mechanically savvy than me that repurposed motors from appliances. My second go/no-go hurdle was wheels. I wanted to use bike wheels and found a bike store that has old wheels that they sell for very little. I ended up getting mine for “free” after buying a chain and gears and some screws from them for about $50. I tried taking apart my kids old bikes but didn’t have the proper bike wrenches to get the pedals off and decided to save my energy and money for other battles. And there were many.
Here’s a link to the motor I have: