HP ELITEDISPLAY S14 New Open Box $85 or BO
+ shipping. New open box
powered and video input through a single included USB-type C cable. You don't need to have Thunderbolt 3 to get this working.... Just need to have USB type C with DP function.
This is cheaper than the next cheapest seller on google by nearly $100 after shipping is included. It's not for everyone as it does add another 2lb of weight to your laptop bag, but if you need another portable display, then it might just be what you need.