As posted on the Buy/Sell section:

Any price via Steam gift in exchange (got a couple of bucks DLC's on my wishlist and Halloween sales are around the corner). See and contact me via my Aeronautico account there. Unfortunately I bought Black Shark like 3 times (1.0, upgrade, 2.0) and never even flown it, so it's a matter of principle.

Airplanes are now built to carry a pilot and a dog in the cockpit: the pilot's job is
to feed the dog, and the dog's job is to bite the pilot if he touches anything...

- Arlen Rens, Lockheed Martin test pilot