MAJOR UPDATE 5-28:
A company called Armor Wear just beat everyone to market with their new AR680 plates. These are Ultra-Hard Steel, and will stop M193 at 3000 fps and above. I no longer recommend AR500 steel plates, with minimum being Mil-HHS (Maingun), and best practices being UHS.
Plates are 6.2 lb. without coating and 7.4 with.
I posted this exact comment on a thread on the ak files a day or so ago... What are your thoughts on this? I was seriously going to pick up some of the ar680 plates after watching the videos on their website until I saw these: