Like everyone the Germans learnt to make things more efficiently, so add a time to any cost figure. Projected costs for the 1,000th a/c of each series, excluding engine(s) and propeller(s) based on a GL Ltd.Chef-Ing. report of 24 April 1941.
Bf 109E = 15,000 RM (the Bf 109F would be the same)
Do 17Z = 41,000 RM
He 111H = 71,000 RM
Ju 88A = 73,000 RM
In 1939 the Germans published a price list for various aircraft available for export. The prices dropped according to how many were ordered. The aircraft were fully equipped. So an order for less than 50 Bf109E would have an individual cost of 162,000 RM. An order for 201 or more would have an individual cost of 130,000 RM. The engine alone seems to have been a fixed cost at 47,000 RM.
Assuming the 201+ order price was closest to the real cost (plus profit) then
Bf110C 290,000 RM
He111P 328,000 RM
He111H 330,000 RM
Hs126 128,000 RM
Ju52 200,000 RM
Ju87B 140,000 RM
Ju88A 305,000 RM
www.econ.yale.edu/growth_pdf/cdp905.pdf Might be worth digging out the audit reports the article uses.
Table 6 you will note the costs are maximum and minimum for the year and the Ju88 for 1939/1940 it is maximum 523,385, minimum 210,648 marks. So if you ignore the obvious high cost in 1939 you are much more able to see the real lowering of costs. In 1941/42 the Ju88A-4 came it at between 170,605 and 167,129 marks, the tropical version between 173,143 and 159,143 marks. In 1942/43 the Ju88A-4 trop came in at between 141,246 and 139,274 marks.
Be careful about what is actually being paid for here, whether Junkers is charging for just the airframe and not all components. Also the later war use of forced and slave labour