Don't underestimate how complex these setups can be.

You need to consider hardware or software routes.
If hardware, what hardware? Combinations?
If software, what combinations? What bugs will you encounter?
Input methods?
Heat / electricity concerns.
Monitor arrangements, wiring, hard drive mirroring.
KVM, multiplexing styles.
Desk design, layout.
UI mods....

Etc etc.

It took me about 6 MONTHS to design and build everything I have now. Granted, I did it all from scratch and my setup is far above what you would simply need to 5 box. But even then, knowing that much of the work has already been done - expect it to be a bit more complex than it might seem at first glance. I HIGHLY doubt you could be completely up and running with a prefect 5 box setup in under a month. It just doesn't happen unless somebody does all of the work for you and packages it. Business opportunity? Maybe. Not one I plan on working on though.