VBkit, if you want to go with a COB option (a bit newer technology), here is what you need (links to good place to buy are given).
Parts
Vero 29 $29.37
Cheap (but pretty efficient) 50W (1.4A) LED driver $11.75
CPU heatink $12.99
Thermal paste (here is a link to an example)
5-12V AC-DC adapter (wall wart).
Some 18 gauge wires (I use door bell wires from Lowes).
AC outlet plug/wire
short M3 screws
solder
Direction
1. The trickiest part is drilling holes to the heatsink, and tapping. It is easier with drill press. Use oil to lubricate during the drilling, and don't push too hard.
2. connect DC side of the drivers to LED with 18gauge wires (+ goes to +, and - goes to -)
3. connect AC plug to the AC side of the drivers.
4. Apply very THIN thermal paste to the LED, and attach it to the CPU heatsink. (note if you are soldering wires to the LED, you should solder BEFORE attaching it to the CPU heatsink).
5. Connect AC/DC adapter to the fan.
Notes
LED Driver: This setup gives about 50W. You can use higher or lower current (watt) drivers. If you drive at a higher current, you get more light, but the efficiency goes down slightly. 1.4A driver is economical (pretty good initial price and overall efficiency is very high). There are better drivers like Meanwell, which can do a couple percent higher efficiency. But the 1.4A driver I linked has 89-90% efficiency from my test (instead of 92% or so of Meanwell). Vero 29 can be easily driven at 100W level.
This setup gives 2320 footcandles and 309 micro mol/m^2/S of PPFD at 1 foot (58.2W of measured energy consumption). But mine is 2014 version of Vero 29, and the 2015 version gives quite a bit better performance than mine.
For orchids (which requires less light than CP), I use 4 units to cover 16 sqft (4x4'). The light source is about 3-3.5' above the bench.
AC/DC apapter for the CPU fan: I just find some cellphone charger or whatever from trash transfer station. 5V or so is enough, and keep the fan quiet.
Heatsink: I gave a link to the one which is pretty good, but I usually find a heatsink from old computers (e.g. trash day).
Solder vs solderless: This can be done solderless if you don't like to solder. Then you need this:
Molex Pico-Ezmate harness to connect wires to the LED
Wago 222-412 to connect wires to wires.
Pico-EzMate seems to work, but it seems a bit flimsy. So I would go with direct soldering.
This kind of setup is frequently used by MJ (and some orchid) growers.
The link to the orchid site which I provided in the previous message has a bit more info.
COB is easier to get lots of light than individual LEDs like XML2. Efficiency depends on the driving current, but COB efficiency (since we usually drive it softly) is similar to XML2, but initial cost is lower with COB. One disadvantage of COB is that it is a point source. So a panel with many individual LEDs spread in a wider area gives a bit more homogeneous light, and it creates less shadow (i.e. advantage of diffused light).