Not sure where to put this although it does involve training/shooting.

I'm looking for some steel plates for targets from 100-1000 yards. What do you guys use and where is the best place to order them? I figure AR500 is what most use. I am mostly looking for silouhette, square/circle, and 1 Gong. I have stands already designed/built but my mild steel plate supply is running dry and I'm tired of punching holes through them.