Tooling charge is not outrageous, are you sure that the minimum run was 50km?
Years ago when I was a designer it was a similar situation for small aluminium extrusions, the big companies had machines with a die capacity for the large double glazing sections etc, my sections were only just bigger than a windscreen seal, the minimum slug of aluminium that they would run through the die taking into account the downtime for the tooling change would have given me 20 years stock of what I wanted.
I had to hunt around and find extruders who specialised in smaller sections to get what I needed, the tooling costs were higher but then the bigger extruders would offset some of the cost against their margin on the production, what cost a lot more was the unit cost of the smaller extrusions or cost per volume if you like but then thats the way of things.
Given that Baines' whole business is small die extrusions, they dont turn out miles of the stuff for the new car industry but focus on the classic market particularly Jaguar I am very surprised at the 50km min production run.
I bet one of the directors is a Jaguar specialist! ?5000 is not out of the question for a lotus specialist if they can envisage selling over 100 sets, ?50 profit of each going to recover the investment but then we are talking about what 600 meters or so? A long way from 50KM