It's the same guy on audizine (flykts3000), he gets them custom made in small batches hence the high price. Audi don't sell the clear lenses separately, only as part of a replacement headlight unit which is £££ more.
I looked on ebay and toyed with the idea of getting some clear lenses from another car which are available, but decided it would look most likely worse than having none. Still haven't fitted my new de-tango'd headlights... Saturday project...