When I upgraded lights from florescent/blurple to QBs, it was a game changer. I went from 55w/sq ft to 24w/sq ft; increased my yield, decreased my bill, and eliminated most of my heat problems.
I then decided I could afford to run more lights so I started building them. Bought 10 COBs. I have 2 fixtures of those completely built and running. For heat sinks I used 12" sections of aluminum threshold, for drivers I tore apart an old mars300 from 2015 and cannibalized the drivers, fan, and wire connectors.
Now I have a total investment of about $350 (plus a few hours of build time) in lights over the past year. Electric bill is about $75 per month steady with 4 people in the house plus 2 reasonably sized grow areas. Cost me about a dollar a watt...
Sorry for the ramble, I am just a big supporter of modern grow lighting be it DIY or high end pre-fab. Lol.