The thrift stores in my area have been terrible for years now, especially Goodwill, which is why I'm surprised so many of you still find a decent amount of stuff there. There are a few decent smaller thrifts, but finding anything there is pretty uncommon. Still, I hit them up if they're on the way to where I'm heading.
One place that I rarely ever checked up until about a year ago were pawn shops. I have a few that I seem to find stuff at most of the time I visit. Most of them are reasonably priced and the ones that aren't slip a lot on pricing certain things which keeps me coming back.
I have also been going to independent game stores in my area more often in recent years too. There will obviously always be games at them and there are a few in particular that charge low ebay or under ebay, which allows me to pick up titles cheaper, but still relative to their current value. I go to the overpriced ones on occasion to and make a game out of catching them misprice games well below ebay; one store in particular has a terribly inconsistent pricing system and it isn't uncommon for me to find one insane deal every time I visit.
I also go to a store called 2nd and Charles which prices their stuff according to ebay, but since their staff has limited knowledge of the collecting market, it isn't uncommon to find great deals there.
I almost never go to my local flea market anymore; it has become 90% resellers and because of that, finding anything cheap is very rare. That combined with a 40-minute drive to it makes it difficult to want to go. I've also never been big on garage sales, but seeing how big some people have scored at them on here and in local groups, I might have to change that for next season.