Schlosser, from Germany, sells on 25 March 2017 a "Circle of Frans de Momper" Tower of Babel as lot 707, estimated at 5,800 Euro.
The work for sale is a bit more sketchy and unfinished than many other Babel paintings, and seems to be a copy: still it is a perpetually popular subject so the estimate may well be right.
UPDATE: the same work is now for sale, on 26 June 2017, at Millon, as a Folllower of Hendrick van Cleve III, estimated at 15,000 to 20,000 Euro. Nice to see my attribution confirmed here!
UPDATE 2: and now, 25 April 2018, for sale at Bonham's as "Circle of Hendrick van Cleve III", estimated at £6,000 to £8,000, or a bit above the original estimate but way below the Millon one. Being offered for sale in Germany, France and the UK in slightly over one year: let's hope it sells now and gets some rest, as it is too good a work to remain unloved.