In my universe, the beginning of accessible homebrew computing was Don Lancaster's TTL-based TV Typewriter and his "TV Typewriter Cookbook". This first lit the spark for me:
A great project in this vein is the Hive retrocomputer [1], which features three Propeller chips from Parallax organized as a master and two slaves. The project "official" language is German though.
I wish we had a modern day radio shack that sold these components off the shelf along with a detailed guide to building it and tinkering with it. It would be a great weekend project you could start on a whim.
Having lived thru it the first time around, RS never really sold that stuff anyway. Its nostalgia.
You'd get some token weirdness of a single device that some buyer got a great deal on, but they never really sold everything you'd need, never all at the same time. Little things missing, like, I donno, static ram. Or canned oscillators, or heck, any crystal other than colorburst xtals. Or eproms. Or eprom burners. Or eprom erasers. That was some of their downfall, I was going to have to send in an order to a mail order supplier anyway, so why not pay mail order prices for everything...
Their stocking was also weird. For awhile they stocked 4116 dram chips which were single bit 16K organization. As used in typical home computers in the early 80s, perhaps. Of course instead of stocking 8 per store (you know, 8 bit computers?) they'd stock like 3 per store. Great job guys, I can see you had a wire direct into the heart of electronics experimenting. I remember paying 19 cents on closeout and using a thundering lot of power supplies and 555 timers and some gates to try and turn a single 4116 chip into a single bit memory, purely for entertainment. I don't remember if I ever got it to work. From memory I think I powered up the triple voltage supplies in the wrong order, blew it out, or static zapped it. Kind of a waste of the other 16383 bits on that chip to only use one bit, but for 19 cents of amusement it seemed a good idea at the time.
Fry's Electronics filled this role rather amazingly back in the '80s (before they transformed themselves into the low-end version of Best Buy that they seem to be today).
My Fry's still has a pretty good amount of electronic "maker" stuff, about 4 retail isles including the test equipment. Of course, that's 4 isles in something like 200k sq ft of "stuff", but it's an awful lot more than anyplace else.
I was in The San Jose (Hamilton) store a couple of weeks back, looking for the Tenma logic probe that their web site said was in stock, but neither myself or the staff could find it. I suspect they didn't really know what it was. I wanted the probe for a 6502-based replica of the Acorn System 1 I am building.
I think it's a very safe bet the staff don't know anything about the test equipment. My experience is that I wouldn't count on them to be familiar with much more than the latest XBox or PS4 game, with the occasional overachiever knowing PCI-e graphic cards.
The old days weren't that great. Today there is SparkFun, https://learn.sparkfun.com/tutorials, which is like 1000x what Radio Shack ever was in terms of Hobby Electronics. And there are hundreds of other sites focusing on Raspberry Pi and Arduino, and then there's the Lego Mindstorm stuff...
The issue today is there are too many choices, so it's a struggle to start. Pick something and go with it. Back in the day, there was very little to choose from! Depending on where you live, there may be hacker/maker spaces nearby with people to help you get started. If there isn't, there's most assuredly Ham Radio people that would love to build stuff with you.
That radio shack existed for about 6 years and then vanished. That said, I really do think such a venture would be reasonably successful. I think in the ideal world it would be combined with a Makerspace (and some have done that).
Back when Fry's had killed off all the shops and had then vacated the space, I put together a business plan for a company I called "Prototype Electronics" which was a mixed use retail/educational shop. With about 8,000 sq ft of space you could build a nice "classroom" type setup and a retail area.
The biggest issue this thing faced was that as a mixed use space it needed some zoning love from most municipalities, the bigger nut though was getting insurance for having meetings on site where people would be using soldering irons. But these days that ground has been plowed with the makerspaces so that landlords are not completely freaked out about it.
Which is available in various places on the web [1] as a PDF.
Andrew (N8VEM) and I got permission from Steve Ciarcia to scan and post it online, as it's long out of print but still in demand.
That was almost ten years ago and I still get a couple emails a month about it.
I had a personal tragedy and sort of dropped out of the Z80 hobbyist community, but I love seeing what Andrew has gone on to do!
https://en.wikipedia.org/wiki/TV_Typewriter