This product is not a steamworks title, thus it will never be available for steam from any other site other than the steam store. If you want the product on steam, you will have to buy it on steam. This is not the case for steamworks titles (such as Just Cause 2, for example), which can be bought on any retail or digital store and the key for the product can be used to add the game to your steam library.
This product is not a steamworks title, so you cannot use the key provided upon purchase to activate the product on steam. The key provided will work on Origin though. If you would like this game on steam, you will need to buy it from the steam store.
FYI, this game is on sale on steam RIGHT NOW for thanksgiving for $4.99. Mass Effect 1 is also $4.99. I always buy games on steam, its just amazing when they have 75% off sales and bundles.. so awesome! Amazon's digital store is interesting possibly, i may start moving over there.