I doubt it as you tend to buy just one & that's it - most cars will already hae one I expect. As a guide Hayward & Scott, who are well known for these, charge about £1500 for a complete system with manifold.
I have seen someone pay £2000 recently. They will pay if they are sure they'll fit properly as there is a tendency amongst repros to not fit & fouling of the steering gear is quite a common problem.
A faithful reproduction & guaranteed perfect fit at £700 would be a good USP. I think they would sell well.
I think there are two types of buyers. Those that want an exhaust that fits at the cheapest price and those that want an exact replica of the original. The trouble with the later is finding a genuine one to copy.
There have been a few threads on this over the years!
When my original manifold rotted I looked around the manufacturers and eventually ordered a stainless one from Stainless Exhaust Specialist, Nottingham who said they had a pattern.
The one they sent looked like a GT one so I sent it back with a spare original from Don Matheson (25 VUR) as well as a copy of the drawing from the parts book and they said they could match it,- which they did, and I think it is as close as it gets.
http://www.stainless-exhaust.com/
It was £390 3 years ago and is a lot darker now than in the photo taken not long after fitting.View attachment 1View attachment 2