I assume that you are not being facetious. I also am not sure if you fully understand what you are asking for.
Can your local shop handle 30mm or so of 5083 or 5085 Aluminum plate, along with steel (including nitrided steel cylinder sleeves), rubber, and glass? As I assume you want a fully operational vehicle, you are looking at about 5,000 or so drawing of the various components, and having to produce, more likely by computer-controlled milling, every individual part, down to the smallest screw, bolt, nut, and washer. Once that is done, then the vehicle is going to have to be assembled, most likely by hand, as this is a one-off product, which is not exactly what robots are designed for. World War 2 tanks ran about a dollar a pound in terms of cost. However, the M!!3 primarily used much more expensive aircraft-grade aluminum, rather than homogeneous steel armor. If I remember correctly from the book, The Industry-Ordnance Team, it took about 2000 man hours to assemble a tank, with not much change with the size of the vehicle. That did assume that the engine and power train was delivered as a completed unit. Your vehicle will have to assemble those from scratch. As an educated guess, I would put assembly time on the order of 3,000 man-hours, and you are not paying those assemblers fifty to seventy-five cents an hour either. Then you have the overhead charges for all of the equipment needed. With respect for ships built at the Royal Navy Dockyards, the Royal Navy included 25% for overhead. You need to factor this is as most US armored vehicles have been built at government-built plants operated by companies under contract. I do not think that you are going to like the final cost.
No I'm not being facetious. I'm looking for an ObTrav application of your credit calculations.
What I'm asking is; how does knowing the original price of an item in its year of manufacture help me calculate its cost in a time when Maker technology becomes ubiquitous?
Obviously an M113 could not be handled by the average home Maker system so i'm assuming a district or neighborhood sized Maker facility that could manufacture vehicle sized objects. Perhaps even a specialist Maker or factory that caters to the reproduction armour collector.
Assume complete designs for a functional vehicle in digital CAD format which I can purchase as a print on demand product or perhaps with limited rights to produce it.
Assume 3D printing and robotic assembly, although for specialist items I can see sub assemblies being bought in (a reason for interstellar cargo) and requiring fitting by skilled labor (perhaps the Tamyia/Airfix of the future will fill this niche, producing special parts and sub-assemblies that can be sent as a kit and integrated into a final product by someone with access to a Maker).
Technically an APC without armament is probably not classed as a weapon, although there might be compromises required such as a powerplant that meets local requirements so there's a variance from the original there.
So if I know the 1963 TL6/7 cost in credits can i calculate the cost to produce the same item at say at TL13?
For this example assume there is no constraint on cost, I'm imagining a collector of reproduction pre-spaceflight Terran armoured vehicles is either a very singular individual or a class of dilettante noble.
But the question is; can I use the "cost of the item as produced in the country of production and the year it was produced" to calculate or extrapolate its cost to produce in another time and another place?