Excellent post. 

I would be interested in buying this machine (or any machine for that matter) if sellers would price their machines according to some type of anticipated return on investment or at the very least, explain their reasoning for coming up with said price.

It doesn't have to be a return on investment in USD but in BTC

No one is in the business of losing money.  Unless I'm seeing something different here, I can't see how I can spend more than like 120 BTC on these machines.