There are many barrels here, and we can see another room beyond that which is also chock-full of barrels.  Each of these barrels represents an investment of €800, so we're looking at quite a substantial sum even if they weren't filled with some of France's best wine.

There are 20 barrels in the top line, 25 on the bottom in each rack.  In round numbers, 250 barrels in this room, maybe 250 more in the next room.  500 barrels times €800 is €400,000; a half-million dollars worth of oak. 

When you buy a bottle of really good wine, a noticeable chunk of the price went to pay for the oak in which it aged.