Today group buying site Joinem launched to the public and announced a $5 million raise from undisclosed investors, including “two senior members of Facebook’s executive team.”

Led by chief executive Darren Waxman and executive chairman Rick Braddock — former Priceline and FreshDirect CEO — Joinem calls itself “the first community-powered digital retailer to monetize the full potential of social commerce.” Yet, on the surface, we’re looking at a familiar demand-based retail model: a high volume of sales can lower the price of individual products. Costco does this, Gilt Group does this, and Jet.com — whenever it launches — will certainly feature aspects of demand-based savings.

But how, exactly, Joinem cuts prices sets it apart from Jet.com, which claims to lower costs by connecting buyers with nearby merchants. Joinem, on the other hand, offers a Mercata-esque model, where the price of its household goods drops once a certain number (say, 25) of customers agree on a set price. Joinem claims this model, which it calls “WePower,” offers up to a 25 percent discount over the price you’d pay for similar products on Amazon.

“The core value in social media is in fact collaboration, or sharing. It’s that value and benefit that we’re trying to lever with this concept,” Braddock told VentureBeat.

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