Yes, you can do high quality with a DIY build but I bought high quality prefab through CF Grow on Amazon, also known as Panda Grow. When I priced out the parts and considered the hassle of a DIY, I decided for the prefab instead. I got a high end component 2 COB unit for $315. It is very nice. I was willing to pay the extra $100 not to have to build it and for a clean, finished looking unit. My next purchase will be a direct buy to China through Alibaba for less than I'd pay to build it myself. Around $200, $179 for 2, around $250 for the new one with the digital "everything" control (timer, temp, auto controls, and power draw displays). This is with top bin Cree CXB3590 COBs and Mean Well driver's. I first bought a little less price tag worthy single for $170. It didn't have the dimmer or daisy chain outlet and is set at 67watts (still love it) but it still is top bin Cree CXB3590 and Mean Well driver. I'm going to use it for clones/seedlings/males. The double is at where I consider the sweet spot. Price isn't bad, has dimmer and daisy chain plug, can use all 200watts, capable of growing 6-8 plants with enough clearance, better in a daisy chain for a larger grow than the bigger units (the bigger ones are just too concentrated).
There are also less expensive versions. Half the price by the same company but they put out a lot of heat and to me that means wasted energy that could have been applied to light waves. Some COB users say the 90 degree concentrator lenses block too many photons and take away from the natural 120 degree angle of the COBs but I like them and my girls are proof they work well. There are also boards with dozens of COBs but they basically do the same thing, cost the same for the coverage, and don't have the active cooling system like mine.
My suggestion, like I need to say it, buy the CF Grow CXB3590 x2 and see how you like it. If you still want to build DIY you can take it apart to see how it's built. I did it for that reason and decided I liked their build so much I'd rather not bother with DIY. Oh, with the Cree COBs you can swap them out for different frequency COBs because the plug into a special mount. So you can use one fixture and make it even more specialised for flower or veg. Other types of COBs are often soldered.
Panda Grow/CF Grow have won me over. And even better buying the fixtures direct through Alibaba and lots of 10 replacement COBs (I'll let you guys know about how Alibaba works out and what import fees for the USA are. Thinking about selling to locals with the specialised COBs.
Here's the Amazon link for my double. It has the option to select the different sises.
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https://www.amazon.com/dp/B06XKW7M9...338OIIDOY9QYX&psc=1&ref_=lv_ov_lig_dp_it&th=1
Of course, these are my opinions and I am a novice. Other experienced growers have different opinions.