They may be just "brown" but so are antaresia!! and they're very popular..
...indeed, and with those similarities we're seeing a price which is also similar
They're neat snakes, they're unique, they have an interesting story, but only the connoisseur herper cares, and anyone who cares all that much has had the opportunity to buy one for several years at a low price. Bright colours are what attract newbies to snakes, and the majority of snakes are purchased by newbies. If you love the snakes, what does it matter if they're cheap? Rough-scaled Pythons are something you keep because they're unique, they appeal to you as a python/Morelia keeping connoisseur, and if that's you, lucky you, you can get them cheaply, and if you love them you'll probably be interested in breeding them even though it's a hobby rather than a lucrative business. If you want to make your fortune breeding snakes, get into Carpet Python morphs, Chondroes or some other popular/new thing (for the record, I don't keep Carpets, Chondroes or Rough-scaled Pythons, although I do like the Rough-scaleds).