Dollars

Many people see the millions flying around when they hear the name of Vincent van Gogh. This is probably based on the few masterpieces from the French period of Van Gogh, which indeed are auctioned for tens of millions. On the other side there are many paintings of Van Gogh selling for a few hundred thousands or are completely worthless.

In broad terms it's the period in which the painting is made which is of importance. The paintings from the Dutch period are much less valuable than the paintings made in France. Of course also the painting itself is of importance.
A painting like "The Potato eaters" shall raise much more than one of the (tens of) portraits of women which Vincent painted in the same period.

There is another aspect which is of vital importance for the value of the painting.

Suppose you own a painting and think it is by Van Gogh. Your car broke down, the cat is ill and your children want to study. You visit Christie's or Sotheby's to have the painting auctioned. Unfortunately they won't do that.

You shall have to prove the painting is a genuine Van Gogh. "No problem" you say, "my brother, neighbour, mother and the milkman are all convinced the painting is authentic".
Unfortunately this is not sufficient. What you need is a letter from the 'curator paintings' at the Van Gogh Museum in Amsterdam. If this curator doesn't supply this note, it is bad luck and your painting is worth zero to nothing.

Plaggenhut met stokken & Vincent van Gogh - door Carl & Ans 2003-2005.