I think the casino will not want to say whether they are buying a source code or rent from the other gambling provider because I believe that will be their secret, and they don't want the public to know one of their secrets. Besides that, I think they will not tell us how much money they use for the source code, and they perhaps only tell that they spend some money to rent the code. At least, they need to keep one of the secrets for their business because they don't want their competitor to know about that secret.
This is probably why so many people prefer Dice games over Slots. You just don't really know your Odds in Slot Machines, it's all about pictures and design but not about the payouts. Especially if there are more than 25 Slot games available, it's very hard to see any differences. For me Slots are only really attractive if you get some sort of bonus. I don't know why but I have been so much more successful with dice games than with slots.