I think I found that deal, except it went up to $439 (it said as $399 earlier). Unfortunately its not CA legal, so it can't even be shipped here.
But its ok because there is the S&W M&P sport II /223/5.56 CA legal model for $449.
https://www.turners.com/smith-and-wesson/smith--wesson-mp15-22-sport-m--441700
Since I'm finding out that 22lr isn't exactly the most reliable ammo, I'm setting my sights on an affordable .223/5.56, plus I've seen some videos where they refer to the .22 as being just a practice gun and not a "real" AR... that recoil though!
And I did figure out the law about california "assault weapons" and it confirms what was in that video I posted earlier (as long as it has a locked magazine requiring the gun to be opened to reload, you can have a pistol grip, adjustable stock and flash suppressor. Without a locked mag, the gun can't have those features)