Im on my second grow w/ a 150 for flowering. . You can grow with one, sure a 1000 HPS would be nice but you can get plenty of use from a 150.
My grow is perpetual, using clones i take 2 cuttings a week and harvest 2 small plants a week.
The pic is from 1 plant from harvest (minus a few popcorn buds). Not a mind blowing harvest, but more than enough for me and the wife for a week.
Im using 1 gallon pots and start flowering when they hit a foot tall.
I topped each plant, and am using some of the lower growth for cuttings. Im clipping off the bottom 1/3 of each plant, the HPS cant get through the canopy so id rather the plant use its energy towards the canopy.