Sub 120 puts you in a kinda tight spot. Not too much more than 120 will take you from a garbage second display, to something extremely nice in no time.
Should the display be driven by USB c alone, or is a separate power brick taking up space acceptable? You say work related so I assume 60hz is fine, but are you looking for 14” 1080p, 16” 1080p, or something g higher res?
For $170 I got a 16” 2560x1600 120hz IPS display and I love it. Sadly they downgraded the model to 1440p but my friend has one and it’s still great.