Don't even get me started on eBay, of course. If you know a specific thing you want to look for, then great. But I've never been introduced to a new concept from there.
It introduced me to the concept cheap merchandise from Honk Kong
. I mean it is dirt cheap. Knick-knacks for a dollar, electronics for half the price of even amazon, etc. Of course it takes 2-6 weeks to actually get into the states (Chinese internal postal service is weird).
It's a bit more refined process then this:
https://xkcd.com/576, but for 10 dollars up front over the month i get all sorts of little goodies I can share for people. Even if it delights them just for a minute it is worth it.