Go on craigslist or something. Say if you can ship me a shadow bass i will pay you x amount of money. If someone offers, describe the shipping conditions needed to keep it alive. Probably going to have to be at least $50. The more you offer, the faster you will get the fish.
Shadow Bass and Rock Bass are so similar in appearance that for every legitimate Shadow you get this way...I'd bet you have a dozen or so Rock Bass. Yes, the pics usually show the Shadow as being much more mottled and splotchy while the Rock is a clean greenish...but there is a vast array of markings to be seen on Rock Bass, which can change their appearance very quickly based on mood, etc. I have caught plenty of Rock Bass that, at least some of the time, looked like dead ringers for what I now see ID'd as Shadows...and I was nowhere near the range of the Shadow Bass.
The Ambloplites genus probably doesn't get nearly the attention that most cichlid genera do from taxonomists. Cichlid genera have proliferated hugely over the past few decades, thanks to the "splitters", who sometimes behave as though each individual fish is a species unto itself. Someday the "lumpers" may come back into vogue and re-integrate them all back together again; the divisions and subdivisions are, let's face it, pretty arbitrary. DNA shows what is related to what and how closely, but taxonomists wanting to get published are the ones who decide whether or not it's a separate species, or just a subspecies, or even a new genus. This happens all the time with birds, no reason it couldn't happen with fish.
So, even if you get some faceless internet seller to send you a couple fish that really are honest-to-goodness Shadow Bass...or at least are considered so today...you might find a year or two later that they have magically been transported back into the rupestris species and are just a regional variation of the same dusty old Rock Bass found across the country. You might feel a little bit silly...but the fish will still look the same in your tank as they always did. They don't care what we call them.
And...fifty bucks for a Rock Bass? Wow.