I acquired a Lenovo PC mini, i7 with 8gb memory and 250tb disk (I upgraded these myself twice, now at 32gb/2tb).
Around 4 years ago it was 6,500 THB used.
I've been very happy with it and will now seek another used model with a built-in Thunderbolt interface, so I can use an external GPU for better processing.
The advantage to this sized footprint, is I can pack it in my backpack, if ever needed, as it weighs 1.5kg. I can easily add up to three HDMI monitors, five USB connections.