I had an Amazon Mom membership which is basically free Amazon Prime for those who qualify, (think buying baby strollers, etc.) It was a great service and I did buy much more frequently. Recently they downgraded the Amazon Mom perks and as such I now think twice about purchasing from Amazon due to the shipping prices and lag time. Had they not changed their TOS I probably would end up giving them much more of my money in the long run.
http://vt100.net/volker-craig/vc4404-um.pdf