Yeah, you can obviously use a much cheaper case if vents are allowed, ambients temperature is not excessive and so forth.
But if you want cheap, you may want to use a cheaper board.
Do not forget that this board is not meant for cpu heavy use . No one will ever use it for decoding , rendering , SETI etc.
Of course people will load that CPU!
It's a great CPU for distributed computing actually. You seem to forget that distributed computing makes most sense when it's not run on dedicated boxes. I run distributed computing on low-power CPUs without fans. If you've got a headless box with an efficient CPU which spends most of its cycles waiting for users to connect, please consider doing so as well.