Maybe COBs aren't worth the bother!
To put some flesh on the bones of the argument for
LED strip with small LEDs vs Big hot COBS, check this
this is a LED strip, made by Samsung and in stock at Digikey (SL-B8T7N90L1WW about $30), which can be paired with the currently cheap Mean Well HLG-185H-48A at BG Micro ($23) and built into a 2 strip "wing" that is 44" x 1.6" at ~120w / 18,200 Lm.
Filling an illumination area of 44" x 44" somewhat like the BML/Fluence SPYDRx (5 wings, $900, 300W) or SPYDRx Plus (8 wings, $1500, 600W)* can be done with this combo for about $400 and $575 respectively for the LEDs and power supplies, but producing substantially more power (665W and 1000W). Even with the additional expense of very nice framing and mechanicals the total price should be quite reasonable. The 8 wing version should have the energy cost of a 1000w HPS but allow much higher PARS ( with closer placement) and a much larger and more even illumination area.
The extreme setups with >8 wings will require fans or something more sophisticated to cool and the illumination levels are substantially higher than Sol, so included here just to show the cost decreases at higher volumes. The ~$1820 / 28 wing setup could be used to illuminate a 5 sq meter area (7' x 7') at a Sol like 100,000 Lm per sq meter.
*SPYDRx W/$ = 0.333, SPYDRx Plus W/$ = 0.4