I am getting into just that myself right now. While no expert, working my way up in experience.I have an expensive slide rule that was given to me in the early 1970s. It was a couple of years before portable calculators became affordable and popular (and slide rules became history.) I remember seeing a few people with calculators when I first started using it. It included a leather case (also in very good condition) and is good to four digits. Most slide rules at the time were only good for three digits. Most of the courses I took emphasized theory, not numeric results, so its use was limited. Then it got put in a drawer for 40 years. I had a working $20 calculator that dated to the 1970s as well. Tossed it in the recycling a year or two ago.
Working used TVs are a hot item in thrift stores (if they get that far.) My experience is that TVs and other electronics that need minor repairs can be sold to people who can fix them. I get a few $ and so does the purchaser once it's fixed. It's not worth spending $100-$200 to get some sets fixed but a tech can make a few $ on the side by fixing them. I see lots of broken electronics on eBay being sold for parts. It the display on a TV is in good condition, chances are it can be fixed.