The Standard Catalog of S&W notes that a genuine aircrewman will lack the upper side plate screw (model 12's had the fifth screw) It will also lack the bolster bushing in the recoil shield that was deleted by the military but kept for the civilian model.
In 2006 the Standard Catalog of S&W gave the following values: Excellent $2000, Very good $950, Good $600, Fair $300, Poor $100. The markings appear to be correct, the US marking on the backstrap is rare and doubles the values above.
I would check the gun as per the above to see if it is genuine, then check on the S&W forum to see if there is a collector with a hole in his collection before returning it. You may be able to make a quick profit, although not a fantastic one due to the frame cracking. FWIW I couldn't see any cracking in the photos.