Obsolete but fully functioning tech is 100% mandatory imo.
No pro will pay close to full retail new value for 10+ year old junk. But it’s still simple enough to use that anybody can get use out of it right away.
From personal experience I love the Canon EOS 20D. Pro-quality DSLR body anyone can use, and still going strong after almost 20yrs. I got one as a very special present when I was rather small and would never be without one.
Go Google the price and buy one. Then buy a bundle of old but compatible gear. You won’t regret it.