Depending on how soon you need this, there is supposed to be another option this 'January'.
Ultra Mobile's
Ultra rate is [supposedly as found in their printed material] 4.9c/MB for data.
I am working on a post for here about 5 newish T-Mobile MVNOs.
One reason I am holding back is one is supposed to have PAYGO in 'January'. With 4.9c/MB data.