When discussing this one of the things that we agreed was that the sealed-box nature of many modern gadgets - including PCs which come with all you probably need - and you can plug in if they don't. People don't need to build or tweak PCs go get good ones, so the knowledge about how they work and how to fix them isn't so easy to find.
On the other hand, if you're so inclined I think the time is never better to build electronic gadgets. In the past there was Capsela
now there's Arduino and other open-source hardware systems.