A pet store is as good as it's people. You can even find knowledgeable staff in the big box stores. I used to manage the exotics department of one. The goal was never to make money on the animals but the set up and consumables. When I worked there (this was several years ago) we received are snakes from reptiles by mack. They would either come in as 'normal' or 'fancy' with atleast 3 meals in their belly. That's all we knew. We paid around $30 for a normal. They often went on sale for 1/2 price at $40. We rarely sold them at their normal price. By the time you factor in the feed costs (by policy we had to offer food every 5 days), bedding cost (1× a week full change plus a heavy spot cleaning and top off on high traffic days) nor to mention labor and vet visits (if they refused food 3 x in a row vet visit was required and you know how balls are)... yeah we lost money on our ball pythons.
Genetics matter to breeders. The majority of pet store shoppers want a cool looking pet. They couldn't care less if it was het for anything.
Back to topic... any chance this guy was in shed? I doubt it is multigened. Maybe a darker lesser?