Not sure what bookstore you're going to, but I don't see any high-quality lessons, handouts, or audio/video resources there. I also think you're interpreting my words a bit literally when you suggest that I Google for "lesson plans for ________." That's not where I stop my search. It's rarely where I even begin my search.
When I'm asked to point out sites that relate to my subject area and to specific units I teach (in essence, to share that very grab bag you say the Internet was never promised as), there aren't such sites because I'm still just trolling the Internet/TV/discussions/movie theater/magazines/novels/comic books/etc. in that effort to find enough to mash together. But there's no set of sites where I always find reliable material.
As far as sites that are targeted at providing such things, there is a paucity of quality. Sure, the quality is out there in separate pieces, but it's up to the teacher to put it together. That's just like saying that anyone can build an atomic bomb: the pieces are out there, all you have to do is put it together.
Nothing does that for me and just about every places that tries does the job horribly -- not because it's necessarily impossible, but simply because they don't do it right.
1. I get most of my books online. But when I do go to the bookstore, my favorite by far is the Museum Book Store at the Baltimore Museum of Art. I don't know if you've ever heard of Amazon.com, but you might start there.
2. You 'troll' Internet TV discussions? Really? No wonder you can't find anything useful.
3. I'd suggest maybe Googling a few major museum websites. Or PBS? Or History Channel? Anything? I trust you'll find something worthwhile. Of course, there's some folks for whom there is no satisfying.
4. And yes. 'Putting things together': if you are a teacher, that's part of your job. Deal.