I'm fairly new to bitcoin and am interested in physical bitcoins.  There are a number of options, but all of the ones I've seen rely on hologram stickers for security.  I think Mike Caldwell is Casascius has documented that he is reliable.  However, once a coin leaves his hands, I am nervous that any Casascius coin I purchase on ebay or through some other vender might be tainted.  Does anyone else share these concerns?  I think some day bitcoins will be worth thousands of dollars each.  There is no doubt that as they become more valuable, that a heightened risk of security will be a concern.  It seems to me that a hologram sticker is pretty weak security.