I live in central California. Which is probably one of the reasons why the thrift stores around me are relatively cheap. If you live around SF or LA, I know it gets pretty pricey to thrift there.
As for the thrift stores I go to, I tend to stay away from the “known” thrift stores (e.g. salvation army, goodwill) b/c they tend to price their stuff a little higher.
I also stay away from the “hipster” area of my town, which has a lot of thrift stores in one location - BUT they get a lot of thrifters, so they know they can jack up the prices.
So, just spend some time going to random thrift stores you find (I just googled thrift stores and my city). You get a feel of the prices and what kinds of things they offer once you go.
As for the ones I go to, I sometimes go to the largest one in my town. Its called Amvets. However, I don’t go there that often now b/c their prices are getting ridiculous for clothes. But, I usually go there for the shoes and bags (not so much their clothes), also to look at cameras. They always have nice Polaroid cameras there. And they usually have sales, but it looks like they pull all of the on sales colored items off the rack that day.
Earlier on, I also use to go to DAV Thrift, since they used to always have 50% of bags. But recently, since they haven’t had a lot of bag donations they have risen the prices for their bags ($8+). & they haven’t had sales for bags in a while. The clothes there are pretty decently priced though. You just gotta spend your time shifting through the racks (like any other thrift store).