That's the standard nodemcu base. Search for that on Amazon - they are about $2.20/ea in qty 5.
The box was pretty pricey as I needed weatherproof (rubber gasket on lid seal, and no penetrations other than the ones I made myself) as it was mounted outside. But I just searched on Amazon for the size I needed and grid base, I think.
If I remember correctly, it is this one:
Gratury Junction Box, IP65 Waterproof Plastic Enclosure for Electrical Project Includes Internal Mounting Panel 250×150×100mm (9.8"×5.9"×3.9") https://www.amazon.com/dp/B07PPYXQSH/ref=cm_sw_r_em_apa_i_rs4hEb7J3Q267
If it were for indoor use I would have done something cheaper. Or if size was at a premium I would have soldered a blank pcb like @Ryan780 mentioned.
