Amazon

Sprint is offering subscribers a deal that on the surface doesn't make a lot of sense.

The carrier said on Thursday its customers can purchase a subscription to Amazon Prime as an add-on to their monthly mobile phone plan. The deal includes all the regular benefits of Prime, including free two-day shipping, streaming video, access to Prime Music, unlimited photo storage and the Kindle e-book lending library.

But here's the rub. Sprint's bundling of Amazon Prime will cost a customer $10.99 a month, which works out to $131.88 a year. Anyone can purchase an Amazon Prime subscription separately at a cost of just $99 a year.

Why charge more for Amazon Prime than the service costs on its own?

The answer is flexibility and convenience, according to Sprint. Since the carrier is offering Prime on a monthly basis, a Sprint subscriber could test out the service and then cancel at anytime. Subscribing to Prime directly through Amazon locks you into a full year.

"For example...say, you're going on Spring Break and need to keep the kids entertained," a Sprint spokeswoman said. "You can easily sign up for the month, watch all of your shows and then cancel when you return -- or, you can send all the books and gifts you want for one month and the next month, you might not need this perk."

Sprint appears to think subscribers will pay more to avoid a long-term commitment and value the convenience of monthly billing. The offer is likely meant to appeal to consumers who've grown accustomed to streaming video on their mobile devices. Sprint's main rival T-Mobile has capitalized on the trend with Binge On, which lets customers watch videos from Amazon and other streaming services without eating into their monthly data allowance.

"This is the only way for someone to get Prime on a month-to-month basis," said the spokeswoman.

However, if you plan to stick with Prime for more than a couple months, this isn't a bargain.