As to how much the gun is worth, about 4-5 years ago, they sold for $1000 to $1200. One of mine, 694106, went to the Boston PD, in about June of 1940, so it was exempt from the ban. If yours went to an exempt entity, then it would have shipped in 1940.
Besides the 6-year late shipment, there is another potentially interesting facet to these guns. Camp Ritchie, now known as Camp David, was being used for covert-activity training, under the guidance of Col. Rex Applegate. Some of the guns may have been shipped there. Ft Mason, in San Francisco, was also thought to be a similar training center. The production of round-butt .38 M&P stopped once the US became involved in WW2: only square-butt revolvers were being produced for the Military. I have a 2" Victory M&P shipped to Ft Mason in either 1941 or 1942, and it was part of a larger shipment. Possibly the special OPs training was still going on there.
Indeed, they are collectible!
Regards, Mike Priwer