Best low-cost, zero admin X terminal?

Dear HN, I'm looking for a way to realize a graphics terminal for remotely working on a Linux server, i.e. I am looking for a low-cost hardware choice and an easy-to-set-up software solution (zero admin desired) for a set of boxes that are to connect to a central Linux server for teaching purposes. What would people recommend? A Raspberry Pi + some Linux distribution featuring X11 R6, or a ready appliance? (Only free and open source software suggestions, please)