 The most valuable item ever appraised at a Roadshow event was a  collection of autographs from every Presidential cabinet member from  George Washington to Franklin Roosevelt, valued at a million  dollars. Not surprisingly, the owner did not wish to appear on the  show. The most valuable item ever shown on the air was a 19th  century Navajo blanket, so rare that only about 50 remain (most in  museums), appraised at $350,000 to $500,000. The owners first  realization of its value came when the shows producers assigned him  and his wife armed guards to protect them and the blanket while they  were taping.