My own AI machine

Hi all,

What would it take to create my own AI machine? I was thinking of a 
LeeLa-like engine.

I guess my question implies:

   * what hardware would I need?
   * what OS would be most convenient/required (Linux-like preferred)?
   * what AI software should I install?
   * what clients would I be able to use to access the engine?

Probably the hardware can be anything between 1 GPU and a farm of GPU's. 
But would there be a reasonable in between solution possible so that the 
AI engine is still reasonably strong and responsive?

Thanks in advance!

best regards,
Jan van der Steen