Here's a link to a very similar one for half the price:
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/332266192577
The only difference I see is the front metal cover screws into the front side instead of the backside. And chip color options..
From my experience, the quality is all the same for the "œChinese" ,for the lack of a better word, low buck lights. I'd make an exception for the black box versions as they are pretty good quality-wise. I've owned a few of the reefbreeders knockoffs and they are very good for the money.
You're right about the company being able to put the units together them-self with better internals, but it's a crap shoot when it's not specifically listed which leads me to believe it's generic.
I ended up with a similar model that had 2 50w chips. They're great for the price; on eBay, but not sure how well they'd do over an aquarium.
Build quality break down:
I took the broken one apart to identify the issue to see if I could easily fix it. The power supply was what died. They ended up giving me a refund. I think I paid $47 for two 100w flood lights (w/o plugs). I'll have to check.
The housing is a piece of molded aluminum
The reflector is a very thin molded aluminum- thinner that a pie pan and very shallow; maybe 1" high
Glass front cover is dyed black around the clear opening and has a silicone lip piped along the upper surface edge that creates the seal when the metal rim is screwed into the unit.
Generic LED screwed to the housing and power supply glued to housing
External hardware all slowly rusted living outdoors after 6mo.
Light never leaked or condensated and was never more than warm to the touch which I couldn't believe because LED's get hot!
I'm not sure how well the extremely wide reflector would penetrate or work without a lot of spillage unless mounted very close to the water, which could start the rust issue.
The 21led website probably puts them together with various parts which is why they offer different chip colors. It would be very easy to swap out with a different colored chip if you wanted to do it yourself.
My perfectly calibrated Kelvin eye would call their "œ6500" a 10k in the hobby or cool white for the rest of the generic led world. lol