Why the heck items on Ebay are mostly in the eastern states?

Because people, in numbers, have been living in the east for a couple of hundred years, or more, longer than they have been living in California. More people means more stuff in their attics, trunks, basements, and barns, more stuff bought by their great-grandparents who lived in the same place 150 years ago. Practically nobody lived in California 150 years ago and those who moved there by wagon train or by car weren't going to bring many toys and ornaments. People moved to California in this century because 1) they were flat broke where they came from and 2) they wanted to leave all that old established settled stuff behind. They went for a new life, not a continuation of the old, and they didn't bring all the stuff from the old life with them.

"rare older"

If they're actually old, then that explanation is rather simple as the Population of California has increased dramatically in the last seventy years. It has twice as any electoral votes as it did in 1948.

So all those old toys were likely sitting in basements or in an old collectors' house and never got moved to the west coast at all.

Just guessing. It's cheaper to live in Pennsylvania or Kentucky, so it's easier to make a living on EBay. Plus, if you've ever traveled through that part of the country, you'll see that historical areas tend to have a lot of antique and collectibles shops (again, easier to make a living because it's cheaper to live there).