A few years ago I was in the UK and saw the rear moulds made by a Euro company. They were solid alloy bar - not hollow, and machine finished. They needed a linish and anodizing, price back then was about 90 pounds a set of 3. Not sure if these are what Motomobil are offering.
I just checked the Motomobil site and theirs are about 45 euro per piece, they are not in stock though. Price is good, but you need to add linishing / anodizing / polishing cost on. Silver anodize is possible as is alloy chrome, last time I got some small parts anodized a local plater charged me $50 cash. Assuming this is still ballpark, $235 plus $50 for a linish and $50 for anodizing, and $35 for the joiner makes $370 for a complete set. Not too bad as a local firm want $100 to $150 per piece to smooth out dented originals.