Amazingly, an original, screen-used TK helmet was discovered by a homeless man behind the Lucasfilm Archives! Apparently he was using it as a hat. Someone had the wherewithal to photograph the helmet where it was discovered, and to do a subsequent detailed comparison. Miracles like this rarely happen anymore, people. It is truly a sign of a higher power watching down over us all.
The discovery site:
Irrefutable evidence of its authenticity:
I happen to have come into possession of this fine beauty and will sell for $1,000,000,000.45 (not including Paypal fees and shipping). Insurance optional.