Simmon's Sporting Goods in Bastrop, LA has a big rack of Kick's GT chokes right in front of their gun counter.
I remember seeing RemChokes in .650 through .670 or maybe .675.
I saw INV+ chokes in .670 through .680 or maybe .685.
They also had Invector chokes, and others.
Note: Their website is a .com, not a .net