"We are writing to provide you advance notice that the price of your Prime membership will be increasing in 2015," it read. "Even as fuel and transportation costs have increased, the price of Prime has remained the same for nine years."
Prime membership gives customers certain perks, like free two-day shipping, free streaming of thousands of movies and TV shows, and use of the Amazon Kindle lending library with free access to 500,000 e-book titles.
CBS News and CNET technology consultant Larry Magid said the price hike may have a marginal impact on Amazon Prime's membership numbers.
"I think some people will drop out, especially those that don't order often or those who don't take advantage of the service's free instant video," he said.
"Personally, I'll stick with the service despite this rather steep price hike. It's still a bit less than what I'll save on shipping over the course of the year, plus I like being able to watch free video which also comes with the service," Magid said.
Reaction from Amazon Prime members on Twitter seemed to echo that sentiment:
While devotees to the service will likely stick with it, CBS Moneywatch found there are some work-arounds to get some of the same benefits without paying the membership fee -- with a little legwork.