Trading wasn't always enabled in Warframe. I think that may be a big reason there isnt one already. It's often in the top 10 steam games by current player count (and steam is not required to play it). Today it peaked at 27,184 concurrent players.
It's free to play, and has tradable real money currency.

This post was edited by birrdd123 on Jan 26 2015 08:59pm

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