makes sense for the owner to be allowed to set the price?
Indeed, I considered this for many hours while I was droning away at work. In the end I decided it wasn't a good idea because it would allow trolls to snipe cards and jack up the prices just so no one else could use them.
It would also allow people to set the price dirt cheap (or free) which also undermines the economy. In the end I determined that this price should be constant across all cards, and that the metric of success would simply be how many people paid to copy a single card.
It would also allow a combination of the two. Imagine creating really popular cards and letting all your friends buy them for cheap before you jack up the prices. Also imagine creating alt accounts and paying yourself to copy cards (I have a solution to this). You can now sell the alt accounts for whatever and that would be the only way to get access to these cards.
We can't have any of this nonsense.
A system like that would get gamed pretty bad.
Perhaps you can tell I've thought about this a lot :D
Thanks for bringing this issue up in the comments though... as it is one of many small parts of the logistics of the game that I absolutely had no opportunity to discuss in the OP.