When Works Norton sell Manx motors do they build them to order and make a profit ?
The factories which make modern motorcycles must rely on economies of scale ?
JAWA stayed in business for a long time, and their market might have been mainly speedway stuff. Their motors were not much more complex than a Commando motor.
Building any production motorcycle out of spare parts would always have been horrendously expensive.
I do not live in the UK. However there seems to still be many small engineering firms there which could be organised to subcontract.
A smart person might be able to figure out the optimum size for an initial production batch.
I have managed a couple of engineering projects - it is not rocket science - just needs application.
If you had a Commando but no motor, how much would you pay for a new motor ?
Just bought and engine, gearbox, and cradle for $700 delivered - normally pay less than that but needed a gearbox pretty quick and have a project coming that I'll use all the engine except the cases to finish. I've bought complete 850s in pretty terrible condition but with engines, gearboxes, cradles, frames, and more that I make look nearly new - the most expensive was $3200 delivered (it was for parts as there was no title).
The most expensive Norton I ever bought is my rider - 100% original, all service records, engine never apart, 11k miles, I picked it up in PA from the second owner and paid $6000. It could use a tank re-paint and I made a new wiring harness and installed Tri-Spark, new tires, and battery. Just changed the original AMALs for Premiers. Even the black cap mufflers that the factory installed look good, and the original rims and spokes are rust free. It was always stored in a heated and cooled garage. In all I have around $7000 in it but it's not as nearly as nice as the ones I sell.
The 1972 bikes have no proper place for a license plate. I had brackets made and I powder coated them in house. I had 30 sets of two made as I was not sure they would sell. All have sold or I've used them. I sold them for $35 delivered in the US. They cost me $25/set to have made and then I powder coated them. Originally the shipping cost me $4.55 per set, the last set cost me $8.65 for shipping. It took three years to sell them. Considering inventory taxes, I lost a good bit of money overall. When I ran out, I asked for the price of 30 more sets - CNC so all they had to do was run them and ship them. The sets were going to cost me $48.16 delivered. I like to help the community, buy I'm not about to loose that much! So, you might think you can easily sub things out - nope! Out interested looked just up what they would cost if I had 5000 sets made: $21.43 delivered per set.
Now with careful use of AN, RGM, Norvil, and aftermarket you could probably build an engine for about $3000 less, but you asked about new and new doesn't include crap parts in my book.
You might think that I could approach AN with an order of all the parts to make 10, 20, 30 or more of them. I certainly could handle that, but please don't think that my cost would be less - AN does not have real dealer accounts - they are happy to sell retail all day - and it seems to be working well for them and to me, more power to them - I'm elated that they exist! If I were such an idiot and bought the parts for 10, I would eventually die with 10 "new" engines on the shelf! I can't even sell the $60,000 worth of AN parts I have now!