Von Zengen, from Germany, sells on 18 March 2017 a "17th century painter" Visit from a polish King to the workshop of sculptor Giambologna, estimated at 1,200 Euro.
It is a copy after a 1701 painting by Balthasar van den Bossche (1681-1715 so not 17th century), and the original says nothing about either Poland or Giambologna; but the clothes of the inspecting buyer indicate Eastern Europe, and many of these works contain copies of works by Giambologna. Van den Bossche was rather prolific and popular, and his works were often copied. The copy has the same dimensions as the original.
It wasn't very hard to guess the original artist, as such sculptor workshops are typical for him; but it was made even easier because the auction house showed a label with the title of the work (which indeed references a Polish prince), which had a handwritten note "B. vd Bosch"...
While Van den Bossche is far from the best painter, the work for sale is on closer inspection clearly inferior. It should struggle to reach 1,000 Euro. For a good Van den Bossche you'll need to pay 3,000 to 5,000 Euro, but the difference quality is quite striking.
UPDATE: the description has been changed on 10 March to "Attributed to Balthasar van den Bossche".
