It dose not look much for £70
It's not the cost of the material or the cost of machining, it's the cost of the work that has to be put in to be able to produce the part. If Chas had ordered 100 pieces the cost would be a lot lower, but could he find a 100 customers? I think not. Not only that to order 100 pieces the outlay would be incredible. I for one would not be prepared to take the risk and lay out that kind of bread.
If 100,000 pieces were ordered for china the cost would be around a fiver, but again what in the hell are you going to do with all that unsold stock?