Tell us about yourself!
You can try Craigslist, Freecycle, or just wait for your elderly family members to pass on tools to you. I happen to have a nice spindle lathe sitting around which my grandfather gave me years ago, but I haven't sourced a motor for it.You can also double check the intro where the author says the >materials< cost less than a dollar. Bricks are available in my area for 95 cents.
Your information is badly out-of-date: https://extension.colostate.edu/topic-areas/natural-resources/rainwater-collection-colorado-6-707/It's not completely unregulated, but it's not like you have to register your barrel purchases either.
Literally: "[The structural engineer] was with me on everything and agreed on its general safety and over-engineeredness."