So, per pot, you'll spend $20 in the first year by my (updated) math, then $5-10 each successive year -- and you'll get about $15 of produce each season. Sometimes much more than $15. Cherry/grape tomatoes are expensive, and the plants are more fruitful than the larger varieties.
Drip irrigation is out of scope. A minute or two, per container, per day, with a hose (or watering can) while you check for hornworms is the operational expectation.
Anyway I don't disagree with your larger point. Little things definitely add up. I've been to IKEA!
I also dislike plastic, but I liked the form factor of the bucket (straight vertical sides) to pack multiples into a small space. I still have the buckets 15 years later, and I use them for all sorts of misc jobs around the garden.
It's a typical reaction when suggestions that gardening can be more expensive than people realize. Yes, if you use the same pots, start taking seeds generationally, etc the price amortizes to near $0. That first year though can put a dent in a wallet. If you've been doing it for awhile, it's easy to forget.
We haven't even discussed getting into drip irrigation or similar. Each of the individual parts are cheap (tubing, sprayers/drippers, etc), but again it adds up with a timer etc.
To be abundantly clear, I'm not trying to dissuade anyone, but just giving realistic expectations. It's just like getting into Arduino and what not. The controller itself is cheap. The shields are cheap. Electronic components are cheap. Then you add up all your receipts and realize, you've spent more money than originally anticipated. It's just the nature of DIY.