Ah, some context -- I live in Vietnam. We don't get tools or books from the 70's and 80s from the trash. New Chinese stuff is pretty good and not a fortune, although at the start I really couldn't afford even that. I was making like 240 US dollars a month in those days, and working 60 hours a week, so I had no free time to do labor-intensive things (or pursue hobbies at all, really). That's why I wanted tools so much I suppose : to do fewer labor intensive things so I could use my mind more.

AVRs are my favorite chips! I use the Attiny10 all the time (USD 0.36 per chip). AVRs have really nice assembly language and datasheets, they are a joy to work with! Attiny10 is maybe a bit difficult to do with the sharpie method. I bet you could with some practice and a very fine pen though.

I etch PCBs by hand at home sometimes these days, because I almost exclusively use SMT. I can usually do a board start to finish in 45 minutes, for iterating rapidly a few times before being satisfied with it. Toner transfer works really well on a gas stove + a big metal plate! However, I can also get boards made at a factory for 15-20$ with a 3 week lead time. That's usually much cheaper than a few 45 minute runs, so recently I've just been sending it off to the factory without etching + testing first.

The main cost is time, overall. I'm not wealthy, time is still super expensive to me right now, I'm in the finishing steps of bootstrapping myself out of poverty. An engineering company was a tool to monetize my interests, so that I could pursue a middle class life, without giving up the control I insist on having over my time and work. Really, it was the only way I could have pursued all this tech stuff at all.

Actual physical tools to do more work faster and more reliably was also really important. Having a company also gives me a 30% discount on tools -- no 10% VAT, and no 20% corporate income tax on the amount of profits it ate up (only if I'm legitimately using it for client work though).

Anyway that's a little slice of my life :)