Not to state the obvious, but -all- art, old and new, cheap and expensive are difficult to sell.

Stolen, famous works come with addition costs and restrictions, not to mention jeopardy.

Art is one of those things with a really long tail. Sure there are the famous artists, who are rightly admired, but I don't want a (legitimate or stolen) Rembrandt on my wall.

I do buy art occasionally. Usually it's cheap. It's always just because it's a piece I like. Honestly, the limiting factor is wall space.