If you haven't already made them, check out the inexpensive, but good ones from Beechwood Casey.
Their web site shows the whole line, called World of Targets.
I use their double spinners for centerfire pistol.
It's a four inch upper with a six inch lower that sells for around $45 or so.
.45s don't even faze them.
For monthly steel challenge competitions in your area, check out the Pickaway Sportsmens Club in Circleville.