At $0.02 per KW, you are profiting on average $320.00 per month for each S7
You have to recoup your initial "investment" (purchase price of hardware + psu) before you see any profit. Even with 2 cent power (which is rare in and of itself) you won't see profit for over a year. That's why I mention ROI even at low power rates. New hardware purchased at retail price just doesn't make any sense right now.
Not necessarily. If you plan on selling the machine, say at half price, you more or less get back your initial investment back at that point. And PSUs.... I reuse what I can, but that's assume you're replacing/upgrading capacity, not adding.
Anyways... my plan is to mine for 6 months, and then see what a used S7 will go for. If I can replace all my miners with a single S7, that's a win, too!
I'm just a hobby guy, though. This is not my day job. Everyone's circumstances are different...
That was my train of thought also. I have my little 'hobby mine' of 2xS3 and an S5 running around 1.8TH avg at just under 1200W. Once the used S7 machines start to hit the marketplace, hopefully at sub $1k prices, I should be able to more than double my hash for the same amount of power. Any amount I can get from reselling the S3/5 machines will help offset the upgrade.
That's also assuming a used market develops for the S7 in 4-6 months. Next week's new technology could turn into vaporware or unobtanium and the S7s will dominate through the halving. Then again, new tech (SP50, et al) could transition the mining game into more co-op operations, even at the hobby level.