I have no idea if Butterfly labs is even shipping those units right now, and even if they are they are heavily backlogged. Any money you save on purchase will be lost in decreased production due to difficulty increase.
I run the hubs off my server, since it is already running anyway, but you can rig a Raspberry Pi to do it if you like. The most cost effective, is likely to run them on a machine that is always on anyway, and using
these 13 port USB panels. I opted not to, since my server is located where my kids could just grab them out, and I decided that was a bad thing.