Looking on Zillow, it looks like a beachfront house on Long Beach Island in New Jersey is ~$2.5-5 million.
Cross the street, go one house back from the beach -- the differentiating factor between the two being whether there's a view out over the ocean -- and the price drops to maybe $1.5-2.5 million.
So you figure that people there basically bought a house plus a window with a fancy picture in it, and that picture cost maybe one to several million dollars.
I wouldn't pay several million dollars for a fancy picture, but I imagine that if someone has done that, then they're probably liable to get pissy if people go and fiddle with it.