Your not going to find a "second hand unit" with a low firmware. If its been used there is a great chance either PSN or a game disk has updated a system. If you look for launch day ps4 that is still sealed thats your best chance. But your looking at big money $500-$900 USD. But l bought a The Last Of Us Bundle that came with 2.04 or 2.05 i cant remember right now and also the manurfacture date will also give you an idea of the FW on the console. http://www.psdevwiki.com/ps4/Datecode But there have been whispers of other entry points in slightly newer FW So.... Your choice. Buy The Ticket.... Take The Ride. Good Luck PS. Been wanting to learn Linux. This seems like a good time.