Come on man lets be real though.  I am a very very very active buyer, seller online and so are most of my friends.  Who cares if someone knows you bought a book at amazon, or a hard drive at newegg.  There not getting any more information then I can find on you by your IP address, and doing some research, or glancing at your mail and getting your name, any trash you throw away, bills, letters etc.  Credit cards are safe, protected with chargebacks, and fraud, paypal same thing, and theres not much they can do with the little information they get when you buy something.  And if your that worried pay with a damn money order from a post office under a fake name.  Bitcoins are only semi easy inside the USA.  The value is extremely sketchy, not much upside with bitcoins at this point.  Yes I understand you might want to keep yourself private with porn, drugs etc but come on, I have been buying and selling shit online for over 10 years now, not much risk at this point.