I'll use a real life example.
3x fans (active intake, scrubber exhaust, and oscillating fan) + light + timer = 205w (and that's with the light on full, it's 125w veg, 155w bloom, timer takes ~2w)
Veg:
18hrs x 125w = 2.250kWh (light)
18hrs x 14w = 0.252kWh (intake fan)
18hrs x 22w = 0.396kWh (osc fan, 18/6 veg, 24/0 bloom)
24hrs x 12w = 0.288kWh (scrub/exh fan)
3.186kWh total (daily, multiply by # of days)
Bloom:
12hrs x 155w = 1.860kWh
12hrs x 14w = 0.168kWh
24hrs x 22w = 0.528kWh
24hrs x 12w = 0.288kWh
2.844kWh total (daily, multiply by # of days)
(3.186 x 21) + (2.844 x 70) = (66.906) + (199.080) = 265.986kWh ... we'll call it 266kWh x (rate) = cost
My base rate is $0.11/kWh: 266 x $0.11 = $29.26 (there are other factors such as time of day that effect rates as well)
... If yields are near what others are seeing, $30 for 2 plants start to finish ain't bad at all.