I would love to take a crack at making some, seems as though its tricky to track down even cheap or otherwise. All the major manufactures make them but acquiring any less than 1000 has been a bit trying.
The closest thing I have seen is the US rapidled’ s cree’s
https://www.rapidled.com/leds/
Even these a $5 a chip will not be cheap when you are thinking about min 8 to minimally cover a 4x4 area