A code for Mass Effect 3 launch DLC, titled 'From Dust', was issued to a customer for $10 (£6).
It is not yet known whether the DLC activation code is genuine, with Electronic Arts and BioWare still to announce plans for downloadable content.
Last month, it was revealed that US website BigBadToyStore is selling Mass Effect 3 collectable figures, which contain access codes to exclusive in-game content.
The 6.7-inch to 7.25-inch replicas of Miranda, Garrus, Mordin and Legion are available to buy for $17.99 individually or $67.99 for a pack of four.
Facebook app Mass Effect Command and recently-announced iOS game Mass Effect: Infiltrator, meanwhile, will give players the opportunity to unlock rewards and increase their galactic readiness level in Mass Effect 3's multiplayer 'Galaxy at War' mode.
Mass Effect 3 will be available on Xbox 360, PlayStation 3 and PC from March 6 in North America and March 9 in Europe.
> Mass Effect 3: Hands on with the first 90 minutes
> Mass Effect 3 interview: How your choices impact the final game
Watch the Mass Effect 3 voice talent trailer below: