I was at OfficeMax looking for a monitor, and my location is nice enough to have a "Tech Clearance" board set up so that all of the clearance items are consolidated. They had the Dell XPS9350-1340SLV for $449.94. The SKU is 471170. I checked Brickseek, and very few stores are $449, probably only the ones that still had one sitting around. Chances are that most of them that you find are going to be open box, if they're still available. And after finding mine, I don't see any available, so please note the EXTREME part of EXTREME YMMV.
OfficeDepot/OfficeMax site page:
Brickseek inventory checker:
The specs are:
13" screen, 1920x1080
8GB non-expandable memory/RAM
Integrated Intel HD Graphics 520
Not sure how good of a deal this is, especially with the Lenovo Ideapad 520S being an 8th gen processor instead of this one's 6th gen, and you don't have to luck out to get the $600 price, but even out the door it's a sub-$500 portable computer with a full OS, backlit keyboard, and IPS screen. If you're okay with the performance specs and want more storage, then the SSD is upgradeable: