Figured this was the best place for this.
http://techcrunch.com/2012/11/06/ama...-amazon-prime/
If you are currently a "shipping only" guest member on someone's Prime account, the option will not show. Removing yourself from their prime won't make it show either. But what I did was:
Remove myself from my roommate's account.
Clear cookies, logged in from my account to verify I was removed. Option still didn't show - only showed yearly.
Sent myself a new invite from my roommate's account. This time when I logged back in (
from Amazon.com - not from the invite link!) going to the Prime page showed the monthly option.
The reason I wanted the new monthly option is because of the way my entertainment budget works and because I no longer qualify for a free one month trial because of previously being a guest account. Yes, it's $12+ more per year this way, but it's still the same price as Netflix or Hulu Plus and I'm wanting to try out Amazon and H+ after using Netflix for ages. The yearly option is non-refundable after the first time you use it. Saving $12 doesn't count for much if I end up not using it enough.