Amazon is making non-Prime members pay higher prices at its brick-and-mortar bookstores

If you're not a Prime member, you'll have to pay a lot more to shop at Amazon's physical bookstores.

According to Geekwire's Taylor Soper, Amazon's bookstores, which first opened in Seattle last year, is offering two different price levels for Prime and non-Prime members.

So if you're a Prime member, you can buy books and other items in the store for the same price as on Amazon.com. But if you're not a Prime member, you'll be charged the "list price," which could be almost 40% more expensive.

Previously, Amazon made the Amazon.com prices available to all customers at its physical stores.

Soper writes the new pricing rules first rolled out in August, across all three Amazon bookstores in Seattle, Portland, and San Diego. The price difference doesn't apply to the Amazon hardware devices sold at the stores.

The pricing change gives an interesting look into Amazon's retail store strategy. With the discounts, Amazon is basically incentivizing its customers to join the Prime program, making its physical stores a place to lure in more Prime members.

Prime costs $99 a year, or $10.99 a month, and offers a number of perks, such as free two-day shipping and free access to video and music streaming.

Amazon has never disclosed the total number of Prime members, but it's estimated to be in the range of 60 million to 80 million in the US. Prime members are also reported to spend more on Amazon than non-Prime members.

Amazon has been launching a lot of different physical store models, including bookstores, grocery stores, and pop-up shops. The new pricing scheme is perhaps one of the many things the company's testing to find the best way to run its physical stores.

Amazon's representative was not immediately available for comment.

Disclosure: Jeff Bezos is an investor in Business Insider through hispersonal investment company Bezos Expeditions.