I love the 6" Black Series figures, and I don’t mind paying $20 for them. One of the problems I see though is resellers. They swoop in and buy all the favorite characters and then sell them on ebay and such for twice as much, or more. Likely your only hope of getting certain ones is to know what’s coming and preorder it from a retailer. Same for Funko, Lego, and others.
I don’t have kids, but from what I gather they aren’t into figures as much anymore. I think adults make up most of the market. I think online is crushing brick and mortar stores too. It’s easier to find what you want online and just have it show up at your door tomorrow. The days of discovering something special on a store shelf are all but gone.