What is stopping me from making my own 3-window bearings?
 

Ok, So the 3 window bearings for the stat gear give more oil flow which is always a good thing but they cost like $40.00 a piece as opposed to the stock bearings which only have 1 window.. What's stopping me from getting out my rotary tool and making my own 3 window bearing? Also, I can just get the stock rotor bearings and use my rotary tool once again to carefully give it a deeper groove?

The only thing stopping you is your brain.

If you have the knowledge & skill to do it, you can do it.