Need help with an EXTREMELY rare Luger

[240to1919]

Hey guys I'm new to collecting Lugers but not firearms. I started after I retired from the Army and haven't looked back. I need help pricing a recently purchased Luger that to my knowledge are only 8-10 were made and even fewer that have been located. It's a Mauser S/42 Precision/Accuracy Test Luger.
The most up to date research on these examples was completed by the Dutch Luger scholar, Joop van de Kant, based on Mauser archives and the recollections of August Weiss, the last head of Mauser Parabellum production who died many years ago. In his new book, The Mauser Parabellum, 1930-1946, at Page 365 he provides the true history of the Üb-marked guns (with "Üb" abbreviating Übung, German for "practice" or "exercise"). He also lists and depicts three more known guns: S/Ns 1413, 1311, and 1316. (These are closer in number to my S/N 1907 example). That makes for at least eight known examples, in two groups, one of four guns in the below 2000 range, and one of four guns in the 11000 range. The key things to know with respect to your questions are the following: 1. The "A" stands for Anschuss, the German word for precision test. 2. The little hole shown in the Kenyon example is by far the outlier exception. It may have been drilled to destroy the barrel, as there were used to the point of near-destruction, as seen in certain other captured arms. The point is that Kenyon was wrong about the theory that these were "pressure test" guns; they were not. In any event, a pressure test gauge would have required a larger hole and a top-mounted gas shunt. To paraphrase Joop, the origin of the guns lies in the problems that Mauser encountered concerning the high percentage of rejected Luger pistols at the final accuracy test (Anschuss) of the military acceptance procedure. In order to obtain the second acceptance proof, pistols were submitted to a precision test. Mauser workers had to shoot one magazine of 8 rounds at a special target at a distance of 50 meters from a bench rest. At least 5 round should be in, or touch, a circle of 17 cm in the middle of the target. When this was not achieved, the pistol went back to the factory for readjustment of the front sight, or even a barrel replacement. Mauser was very concerned about the high percentage of rejects at the first presentation for this test. Therefore, the next steps were introduced during mid-1935 (confirmed by a Mauser document I have seen and read, and which is in Joop's book): 1. Out of all workers the best marksmen were selected. 2. A bonus was offered for these marksmen when they could improve the rate of accepted pistols at the first attempt. This bonus went from 1 Pfennig for a rate of 31-35%, to 4,5 Pfennig for a rate of 70% or higher. 3. These marksmen were invited to practice target shooting in private time. 4. For this practice, an unknown quantity of so called and marked Üb pistols were assembled from obsolete parts. These pistols were kept in the factory and issued to the marksmen during their exercising. The first Üb marked pistols were assembled in 1935. In view of the growing production numbers of military Luger pistols produced per month thereafter, more Üb marked pistols were added during 1936-1941 (evidenced by some, the rarest, with a byf toggle, which could only have been made in or after 1941). The Üb marking is observed mostly on the chamber, also on the wooden grip panels and some on top of the barrel. These pistols are mostly non-matching, and a mix of DWM, Erfurt and Mauser parts is reported. They have nothing to do with hypothesized "tool room" or "pressure test" pistols. About half of these pistols have also the "A" stamped on various locations like the barrel or the grip plates (or both). As described on page 300 of “Lugers At Random” by Kenyon, this is a Mauser (S/42) pressure-test Luger, pieced together with mismatched, unfinished oversize parts off the production line to test chamber pressures. Per Kenyon, less than 10 of these guns were ever produced, and his photographed example is, per him, the only one known to exist, However, our research indicates that eight, and possibly, as many as 10 of these guns are known to exist - it is nonetheless a VERY rare gun. I believe this gun was “liberated” from the production line before the pressure test hole was drilled in the barrel, however it may have never had a hole, there is debate currently as to weather or not all of these guns actually had a hole drilled. . Sans this hole, everything else matches Kenyon’s description, including the “A” marking on the barrel “UB” on the receiver atop the 1939 date and “LW” on the right side of the receiver. The grips are marked “EW” on the right grip and UB, A’ on the left grip. The gun has a rough finish, but overall condition (grips, finish and bore) is 85%. The only history we got on this gun from the seller was that he purchased this piece, and some other guns from the estate of a WWII Veteran who had just passed away. I would like to know what the value of this pistol is. I've been told anything from 10,000 to 25,000. I've even been told its too rare to price. I tried to upload my photos so ill try again later and see if I can get them up. Any help that you guys can give me I would be grateful.