My most interesting find was a UK bargain bin copy of Gunman Chronicles. I live in the US.
Sadly, the few times I've gone thrift store hunting was mostly just old clothes and furniture. I haven't found any places that have electronics, old PC parts, etc, and I'm pretty sure the only goodwill store in my area puts anything vaguely tech related on their web auction site (despite living in a city, there's only one goodwill store that I can find now, the rest have not only been turned into drop-off only, but haven't updated their Google maps info, so it's impossible to tell if there are other actual stores in the area).
There's a pretty big goodwill store where I live but word on the street is the prices aren't thrift competitive anymore. The real big block thrift is value village but the parking is terrible and there's no way to get there by bus without walking for a mile