Ooh, the Prometheus is such an interesting ship. I love it but, the Katana is soo much more my speed. Or the... Flax? However, if you start a new game with budgeted game start, you should be able to add the prometheous to your known list of blueprints (I did).

Such a nice trader :) A little bit light on cargo space, but it's speedy and reasonably well defended :) And as a personal ship its pretty great :) Handles better than a Katana if I remember correctly :) Though it does cover half the screen when you are piloting it :(