When I cruised the Destiny four years ago, the art auctions were incredible. They had Dali, Picasso, Disney, Warner Brother's, you name it. The price ranges were anywhere from $5.00 up to $10,000. One thing I found was that the starting bids were all quite low for the caliber of the artwork. I could have gone crazy! I did pick up two Indian artwork pieces commissioned by the White House to honor the Native American Heritage for $110.00 for both. The nice thing was that Park West Galleries, based here in Michigan was able to ship me the pieces so I did not have to get them home. I was charge correctly to my sail and sign card and the artwork arrived three weeks after returning from the cruise (ahead of the scheduled four weeks I was told). There is a terrific selection. During my cruise, we had a lot of poor weather that kept us in the ship with an additional day at sea (Grand Caymen was closed to cruise ship traffic). So we ended up having three art auctions. I was really surprised to see that there was some of the same stuff, but with each auction, new pieces were added that I hadn't seen the time before.
Now I can't compare to this to other cruise lines, but I was very impressed on all levels with the Carnival art auctions. And if you do follow art, Park West in my case is one of the big dealers of art. I don't know if Carnival still uses them, but if so, I don't think you will go wrong.