I'd expect them to be cast ally due to the weight (they're quite heavy), durability as a road wheel (you need to watch for cracks in mag. wheels) and the cost to TVR.
Lepsons charged £230 for the four although apparently had they realised before they quoted me that they were magnesium they would have been slightly dearer. Their prices are on the web.
They have done a good job on them they look like new.
