The Rise of Flight store opened up just today, making available five aircraft available for purchase: the Nieuport 17.C1, Nieuport 28.C1, Albatros D.Va, SPAD 13.C1, and the Fokker D.VII. All planes are currently available for $7.62 (€5.45).
Of course, many of these planes have already been made available, as it was announced earlier that the developers decided to give US and European customers the Albatros D.Va and Nieuport 28 for free.
The store also clears up a frequent misunderstanding about the aircraft: "Please note that all flyable aircraft available for purchase are already in-game as non-flyable A.I. controlled aircraft." What this means is that you're essentially only playing for the cockpit and the right to fly in the cockpit. You will still be able to shoot all of these aircraft down without paying any extra money!
Each aircraft in the store has some really nice artwork and a good description. For example, here's part of the artwork for the Albatros D.Va: