Great experiment, and it looks like a lot of fun. But to be practical, the amount of time + effort + risk required to pull this of would offset any amount of money saved.
The monetization made off of Youtube should offset all of that and then some.
Yeah, I can imagine him turning this into something similar to the "What's Inside" Family" where the goal isn't so much cost-saving vs exploring how things are made.
What's the risk?
Presumably the risk of screwing up and needing to repurchase certain parts and/or spend more time creating it.
His $5 battery exploding
Risk of buying a useless or counterfeit part that doesn't end up working in his build.
I don't know, is it possible that activating iOS might be rejected because the logic board serial number is blacklisted by Apple for any number of reasons?