I've upgraded from 8gbs to 16gbs and 1tb to 500gb ssd - total cost $140. The laptop is a free handmedown with a i3-5010U (dual at 2.1).
I really like the idea of the 'toughbook' but would rather build my own. I'd like to practice fabricating case mods out of wood, lol.
It would be thickened with a sheet of plywood - router out paths for air pockets and parts.