Air Buccaneers is on sale for €10.00 / $13.05 (50% off) for first week of beta direct from LudoCraft. BTW, I did a currency rate calculation to get that USD price.
This game was just announced as one of the games that has been greenlit on Steam. LudoCraft has posted this to their page:
Naturally all purchases made before AirBuccaneers lands on Steam, will receive a Steam activation key once it’s released there.