I think 8-bit CPUs are great for introducing computer technology, and they also lend themselves to discussing computing history from the 70s. Though a little more expensive than the author's target of $100, the fellow who designed this educational CPU board (https://kswichit.net/6502/6502.html) sells them (assembled) on eBay for a very modest amount of money. I have used these with students, and we had a great time with them. There is even a crude online simulator of the board that emulates the LED outputs (https://tiggerntatie.github.io/kswichit-6502/).
I've never considered assembling projects the fun part. that's the "ok whew done, I hope I didn't screw it up," part. it's not even an educational part of the project, unless you are educating on soldering somehow.
