Price = WorthA famous painting in museum is priceless as long as it remains there as a priceless piece of art. At the moment, it is out, every painter can paint one alike and it may loose its worth. So here priceless-ness ended up as worthlessness.
However, Priceless <> Worthless
But the other theory states it differently, the painting is now hung on the wall of every adjacent house - so its more popular, hence it was worthwhile to take it out of the museum to get more price. So here the formula gets reversed. A thing that became worthless earlier being out of the museum, is now high priced. But remember, you may no longer call it "priceless".
But I would always prefer the priceless-ness of the originality of the painting in the museum. The priceless things are very precious, and so let them be. Do not force things to make them worthless.
Stop Piracy :-)