I turned down the chance to buy an autographed copy of Groucho's autobiography for $15 once.
Unfortunately, it was autographed by Cavett.
-- mnw
PS: Actually, it would've gone well with my copy of Naked Lunch, which Dr. Hunter S. Thompson's cohort Karl Laszlo had insisted on signing for reasons he never made clear!
PPS: Back when I was hanging around with some ex-Mansonites, I had the one who called himself "White Rabitt" (sic) sign the appropriate Jefferson Airplane LP ("Surrealistic Pillow"), and I later scored big bux off it via Ebay!