How to find Junk yards
When I was starting to tinker with electronics, I've done a fair bit of resourceful activities, such as junk yard scavenging and dumpster diving.  At the time I lived in Russia, the year was 1992, there were no interwebs, electronic components were very difficult procure.  DigiKeys and Mousers were out of the question; the concept of catalog distributors wasn't known.  For the most part, scavenging was about the only option.  Electronics components were currency between our little group of friends.

But.  There is a problem with scavenging, especially with scavenging out of modern appliances.  You don't really know what you're getting.  First, you need to establish if the component is in working order.  Even if it is, you may or may not be able to identify it and to find its datasheet.  Suppose you get lucky and you make a device with a scavenged component, which works.
And it works well.  And you want to build another one.  Where would you get another one of those scavenged components?  **

At the same time.  Price of components is comparatively low on catalog distributors such as Jameco, Mouser, DigiKey.  For $10 worth of new parts, one can get a fair bit of tinkering done.  Importantly, the parts will have datasheets.
cardinal rule:  No datasheet ⇒ No sale

Still.  Taking apart various devices is worthwhile.  Not because you can scavenge parts, but because you will glean design ideas.  Medical and military electronics is particularly interesting from this standpoint, if you can get your hands on it.

**  Similar procurement issues occur with surplus parts.  So called "new from old stock".  I had a mentor/boss, who would consistently discourage surplus parts in the R&amp;D lab.