I have come across a lot of older games just by people knowing I am into gaming. I have gotten an NES with a pile of games, 3 controllers, and two zappers for free all because I wore a mario shirt once. They also had a broken SNES pad in there which I converted to USB.
Another time someone game me a box of unsold gameboy stuff from a tag sale. 20 or so games, 2 original gameboys, and various accessories. Again, free.
When it comes to collecting, I tend to not bother unless it is something I have personal nostalgia for. I could never see myself buying something like Earthbound (unless I really wanted to play it) because I have no nostalgia for it.
I also love finding and playing games that are not available without piracy or actually owning the original console. Some games just never make it to virtual console. That being said, I turned around and sold most of the gameboy and NES stuff to purchase other things.