PS3 to run Linux on discussion

Hey, so I want to get a backwards compatible PS3 that I can run Linux on. Any idea where I can find one that guarantees the proper firmware? I'm willing to spend up to 400$ to get a working system with the right firmware. I was hoping for at least 60 GB of initial memory, but I'll settle for less if need be.

BTW, I would prefer to have as much memory as possible since I will basically be using this a computer and any money saved on the system will go towards upgrading the individual pieces of hardware.