I am not sure whether to buy it or not.
Where to buy them in this price?
Not bad at all.
So if you would buy 5 of them costs will be repayed in 1 month?
Or I don't get it right?
No it would still take 5 months and depend on your cost of electricity plus the price of BTC, etc.
Yes indeed my math seems not too good in this case
Indeed if you will buy 5 you will pay 5 times more so it need 5 times more time to recover costs but we have 5 times more devices so yes indeed still 5 months and maybe even more because like you said of electricity price.
But as well after 5 months profits would be 5 times bigger