Back to your original question, I’m working on my first Ignition project and have set up an Ubuntu server with some HP t5565 thin clients (~$235 ea.). They have a 1Gb SSD and 1Gb RAM and run an HP OS that is actually Debian Linux and comes with just about everything needed pre-installed (including the Java jre) and an ELO touch driver.
While I haven’t put this into production yet, from what I can see so far, they appear to work quite well for this application.