I made some evaluation a few months ago because I decided to replace my old DIY monoball camber plates and found them too:
Short said: Stay away, poorly machined and cheap monoballs.
There are several good products I would recommend:
-Tarett or Elephant ones (same product)
-Mode (what I ordered)
-Tarett Catridge for stock plates
Check my thread too:
Uniball camber plates yes, but which one?