Am I missing something? It doesn't seem to make sense to buy an S9 at the current prices.
ROI is beautiful in these T9 and from what i have read they are very reliable, they lowered the price to 755 with PSU. If you have 420$ coupons u cant beat that ROI. My power cost is around 0.05$
Your ROI calculations are off you are not taking into account raising mining difficulty. Also shipping is kinda expensive around 110$ per miner i bet you can find some 420$ coupons for around 50-80$
It makes sense buying a 14th/s S9 if u dont have cheap electricity, they are a lot more efficient...
I wonder how it will be if I trying to buy T9, my electricity fee is around $0.12 / kw but unfortunately, I don't know much about how to calculate the fee in a month. the shipping is too expensive but maybe it could worth if we can get some coupons to buy. I think it will worth again if bitcoin price can increase higher.
$0.12 / kw is your price per hour. The T9+ consumes about 1440 watt per hour, so your hourly cost for operating one T9+ is going to be $0.1728 (Daily cost is $4.1472 and monthly cost is $124.416). Currently the T9+ makes around $5.83 daily (~0.00073 BTC). You will make around $50.484 monthly after electricity assuming that network difficulty and Bitcoin price will stay the same. Honestly, in my opinion I would rather buy bitcoin instead of buying the T9+ in your case. You can make the final decision but don't forget to factor in network difficulty and future bitcoin price.
Hope this helps. Merits are appreciated.