Of course its fake. It didn't come from Mars so it's not "Martian" soil. 

Also since they cannot verify that their "formula" is correct and actually duplicates the soil on Mars, this is another reason it has be deemed fake.

They most likely received multiple, LARGE grants to undertake this project, now they are making MORE money off it? Well welcome to the US where everything has a price and can be sold. 

Dirt... I mean its dirt folks. Scoop some out of your back yard say it "possibly" (to avoid those pesky legal proceedings by the offended Martians) Martian dirt and sell it for $15 / kg. Undercut them. 

Personally I don't see the point. Its not a collectible, it didn't come from my Mars so you don't have anything special. How do we know its the final product? Did they mass produce this already? If so why? If not, then its probably one of the earlier "failures" and again is not real "possibly" Martian soil.

People will buy anything and this is proof of that