Most places don't carry blue cats for stocking seeing as they get too big for ponds. Some of the south eastern states raise them commercially or for river/lake stocking but they wouldn't ship them. Your best bet is going to be trying to catch one. I'm not sure if there are a lot of them in the rivers in Ohio but in Kentucky and Tennessee you can catch them fairly easily by seining or setting twig lines or troutlines. Catching one the size you want will be the issue. You will also end up with a lot of channel cats and a few flatheads. A flathead would look awesome is a huge aquarium or a pond. The bass pro shop in Nashville currently has a 90lbs blue cat in the display tank.