Not sure where you are from but I have two rivers near me that have Rock Bass. They sure do put up a fight for their size. I haven't fished those rivers in a couple of years though. There may be a vendor that sells native fish online but I'm not sure. Other members may know where to get them though. In some states there are places that sell minnows all the way up to Bass for stocking purposes. GL
I have checked a fair few places at least online but I don't think there are anyone that I know of that sells them so if I really go through with this I will catch one myself but I'm still learning and finding out about fish that just seem like a smarter idea sometimes, idk I'm still looking.