Düsseldorfer Auktionshaus, from Germany, sells on 4 May 2018 as lot 135 a "Dutch, 17th century" oil on panel estimated at 200 Euro.
It is a typical amusing moralistic painting in the tradition of Teniers, but I haven't found another version of this one. it looks as if the farmer spills either money he is paying to the milkmaid, or seed, from his hat, when he is startled by the dog. The milkmaid at the same time is spilling milk from her yoke. She is perhaps carrying grain or seed which she offered to or received from the farmer, or money she received in return for some milk, although the farmer has nothing to carry the milk in. Of course, with a farmer spilling his seed and the milkmaid spilling her milk, there is a small chance that some subtle sexual innuendo is hidden in the painting. Subtlety wasn't always the strongest point of these artists!
The story isn't exactly clear, and the painting is not made by a major artist, but it is an amusing and relatively unusual 17th century work, much more fun to own than the usual second-rate crucifixions or unidentifiable ugly portraits of long-forgotten sitters, and at 200 Euro it is very cheap. Somewhere closer to 700 or 800 Euro seems reasonable.
UPDATE: a reader informed me (correctly) that the work is a copy after (or more likely an original by) Adriaen Van de Venne (I didn't find the exact work this is based on, but multiple others from the same series), and that it sold for a whopping 8000 Euro, or 40 times their and ten times my estimate. Looking again at the picture, I wonder if there is some signature or date on the rock left of the inscription, but the image is too small to make this out.