Is this a Trick Question?
I know your immediate answer will be comic book shops and you wouldn’t be wrong, but here’s some other places.
The first comic books I ever received were won by my uncle at an auction house. They were hidden inside a wardrobe that he.That’s the fun thing about auctions, you might win a little bit of anything.
Thrift shops do have a little bit of everything and sometimes they’ll have comics. I have gotten polybagged sealed comics at Goodwill.
A lot of people have no idea what they have and are STILL selling their kid’s comics. Most of the older people I know that collected as a kid, don’t have their comics because of their parents doing this.
Bargain stores like Ollie’s
Ollie’s is a rare kind of discount store . They sell small packs of comics and also single issues.
Used Book stores
Many stores that sell used books, often sell used comics as well. It’s not every used book store, but many will surprise you,
I want to say a good thirty to fifty percent of my collection comes from eBay. But there is also Midtown Comics, My comic shop, and so many others sites you can use.
Yes, DC has had multiple partnerships with Walmart. So if you are at one of their selective Walmarts you can find packs of comics there.