Dell 22" Touchscreen Monitor S2240T - S$66
Raspberry Pi 400 - S$113
Micro HDMI to HDMI - S$7
SanDisk microSD 32GB - S$6.80
The USB-C PD adaptor I use is from my broken RPi4 so it's free.
The S2240T also comes with an audio out jack where I use my old ATH-M50. You can also use a bluetooth speaker with the Raspberry Pi 400.