Spent $400 on a portable monitor in Chiang Mai and it's the best dumb choice I ever made

I was trying to work from a tiny cafe table with just my laptop, and my neck was killing me after two days. I bought a 15-inch portable screen on a whim, and now I can set up a proper two-screen workstation anywhere, even in a hostel bunk. Anyone else find a piece of gear that seemed silly but totally changed your work setup?