Bloomberg is reporting that those rumored HTC Amazon devices we’ve heard so much about lately may come with heavy strings attached. The news agency is saying that the devices (plural) could be sold to Prime members only. It may sound limiting, but could be a winning strategy for Amazon moving forward.

While we’ve long heard Amazon is working on some form of smartphone, but often have little more to go on after that fact. Wild rumors fo a 3D device pop up now and again, though nobody is willing to comment or relay info regarding specs aside from things like eye tracking cameras or the 3D display. Amazon is said to be working with HTC, though that poses a question regarding HTC’s involvement in the OHA.

While the Amazon Kindle family of tablets definitely works best with a Prime membership, it’s not mandatory. Bloomberg didn’t note whether the rumored smartphones would be sold only to existing Prime members, or require a Prime membership.

While it’s still only rumor, we find it plausible that Amazon would insist on a Prime membership for a free smartphone — or even a series of membership options for multiple devices. Much like Google sells the Nexus devices at near-cost, so does Amazon with their Kindle tablets. At the end of the day, smartphones and tablets are conduits to consumption, and Amazon’s marketplace is hard to beat for media.

Something like a prepaid, two to five year Prime membership for this “free phone” scheme sounds interesting. While we get a free phone, we’d be tied into Amazon for five years or so. If we dislike the device, we don’t even have to use or keep it — we’d be tied to Amazon, not a device or rate plan. If the real endgame is consumption, that could be a winning strategy for Amazon.