when i used to make themes, i sold them at 2k. and a lot of people would buy them. but then i saw them on the marketplace and people were reselling my themes for 20k.
so i bumped up my prices to 20k, and no one buys them. feels bad.
you can't dupe other people's creations. you can only buy them, sell them, or mail them. but the duplicate option is not available for other people's creations.