yes and no.

If I have 12 k-watts running 10 s9's I earn

130 x 0.08 = $ 10.40 or 300 a month

I use about

 8640 k-watts a month

at 1 cent that is   $86.40 in power    net is 214 bucks I would buy 2 s17e or t17+
at 2 cent that is $172.80 in power    net is 127 bucks  I would buy 1 s17e or t17+
at 3 cent that is $259.20 in power    net is   41 bucks  I would buy 1 s17e or t17+

look at ratio and mix of efficiency and gear price.

note cheap power or next to free power ie 0 to 3 cent power.