The Initiative Fighter model is only available when Ryder has access to William Spender's quarters during Nakmor Drack: Krogan Betrayal.
During the course of the investigation in William Spender's apartment, Ryder can find this model. It is free for the taking, but SAM will point out that it is stolen merchandise and asks if Ryder is putting it back. There are no negative consequences for taking the model, even though Ryder's response is "finders, keepers," rather than "I'm confiscating the stolen goods."
If you don't take the model while you are here, you will lose access to this area and the model forever.