Here's what I know: About four months ago, I e-mailed Powder Valley asking if they ever get any primers in. The reply said yes, however "bots" buy them as soon as they are posted, and they are trying to find a
work-around to eliminate it from happening. They've instituted a policy that if items are placed in the shopping cart, but not purchased within 15 minutes, the cart is automatically emptied.
I remember the bot thing during ol' Barry's reign, and a web-site called Ammo bot, or some such. I don't know how to set up a bot, but as long as bots are doing the buying there's no reason for the sellers to lower their pricing.
Regarding Midway, I've never bought their primers or powder, but it's my understanding the company doesn't stock those items, and that they rely on a third party to ship them.