I think as most of ns... you should get it for you and your friends.... insurance will be so expensive...
i have here in my house in Spain a "minipark" that i´ve done alone, all with free stuff and my own work! I think i´ve paid like 150€ or less in total. I have 5 features, tgose that u see in the photo and some more (the 3,5m down rail, a 4,5m flat rail, 4m flat box, 4,5 steel flat box and a 2,5m pvc box)
The green plastic grass was picked from a work under construction for free, and the wood for the inrun of a friend for free also.