CDNN has some "target sports" Mossberg 500 barrels listed for sale for $69+ ship if anyone is looking for one. I thought it was a decent price, so here ya go:
https://www.cdnnsports.com/too-cheap/mossberg-500-28-inch-barrel-with-vent-rib.html#.XDJFrGDsbcc
https://www.cdnnsports.com/too-cheap/mossberg-500-28-inch-barrel-with-vent-rib.html#.XDJFrGDsbcc