They have lots at my local HD
- even comes in 3 different colours! May be yours just stock them in a different spot? In the local HD
, it was not in lighting, but with the mouldings & wood trims. < Beats me on the logic of that!
You might want to ask where they stock the ceiling light panels next time you are there. The eggcrates are pretty common here & just about all the DIY
stores stock them here.
Any plastic grate should work, IMO
. However, the eggcrate is much cheaper (about $6 for a 2x4' sheet). The return vent grates cost much more (something like $10 for a 16" vent).