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.
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.
When I grew tomatoes in containers, I went for the 5-gal buckets from Lowes ($4), and bought soil in larger bags. Also your cage is more expensive than I recall paying.
On the plus side, most of those are one-time startup costs.
Our tomatoes are self-seeding at this point. We literally do nothing except pick them, and put away several dozen jars of sauce every year, from a couple neglected garden beds. It sounds like we have less trouble with pests here than you do though.