Here is an IM exchange from today:
12:46] Maryann Coanda: (Saved Sun Oct 12 14:35:42 2008) hi, while looking for treasure in your store, i accidently bought clouds, blue for $500. can i please send it back to you and get e refund?
[12:54] Enjah Mysterio: I am sorry, Maryann, I do not give refunds for items that are no transfer.
[12:59] Maryann Coanda: well, enjoy my $500
[12:59] Enjah Mysterio: and you enjoy my painting; there is no way for you to return something that is copyable. I made it copyable so that people can pull one out of inventory in case one gets lost somehow; and I stopped making my paintings resaleable because I found people were selling them for far more than they paid.
[13:00] you had a dialog telling you you were about to buy it, and you have been in SL for two years, so you knew what you were doing.
[13:01] Maryann Coanda: ok, nothing i can do about it, a lot of money for clouds, but, my mistake
[13:01] Enjah Mysterio: I painted it, and actually, it is about $2 USD that you paid for it, so live and learn I guess; cheap lesson.