The best value are in the kit form but diyled will assemble them for free for you. Not that its hard, its a couple of screws and a plug.
You wont be saving huge amounts on electricity. I saved a bit, not that I count my electric bill, I used to run 1.5x 600w hps over 4x4 (3x 600w over 8x4) so I swapped one side for two 260w kits. So swapped 900w for 520w.
But your looking at 520w vs 600w, the 520w pisses all over 1 600w hps.
At the wall it will be 570w for the QBs vs around 660w for the HPS, give or take a few watts because different ballasts are more or less efficient.
Other options are 400w of strips. That would be around equal to 600w of hps, saves a bit more electricity gets same yield ish.
A HLG550 , USA only (horticultural lighting group) A bit expensive.
A HLG600 from growers lights (USA) Similar wattage (to the HPS) higher yield, tiny saving on electricity. Better value than 550 IMO.
Cant really beat the double 260w kits from diyled.co.uk, More yield, slight saving in power cost.
No taxes to pay from importing and cheaper deliver cost. Plus he can be contacted on here if advise is needed.
Plus with two lights instead of one big one you can adjust, lower or raise for better coverage.