The Big Goodbye

Could you imagine a time in your prop-collecting life when you would be ready to say goodbye to your things?  Dave and Ryan certainly cannot... but they are joined by Aliens super-collector Harry Harris who made such a decision and recently auctioned off most of his incredible precious-es.  What drives a collector to sell?  When is it time?  Are there regrets?  Will Ryan and Dave be buried with their collections like Egyptian pharaohs?