In Stock Again.
Let me guess not profitable at $400, so it's out of stock. Soon as it's >$450, magically in stock again.
It's a miracle!

I think Ninjatech has S1 in stock
Usually Ninjatech orders directly from Bitmain though. So, if Bitmain is out of stock, then Ninjatech is too.
When I ordered from Ninja, the label said it's from Shenzen China, not Arizona where Ninjatech is based.
You probably right ChuckBuck.
Ninja wrote something about having new/used units available, so I thought he might have them in stock.
Why do you think the S1 are geting hard to find? Bitmain stop making them?
They probably winding down S1 inventory, to ship more S2's instead.
They're also probably working on their next generation miner at the same time.