AFAIK, there’s no Albatros “just numbers” available. Since it’s only the digits you require, you might try 1/32 FCM Albatros sheets, cobble the serials from Roden Alb. DI/D.III kit decal sheets, or Pfalz D-Type sheets. The Pfalz fonts are close enough that none but the purist is likely to notice the difference. Pheon 32012 is out of print, so you’re not likely to find it at a “reasonable” price, especially since you’re only looking for one airframe.
As for D.2119/16, I could only find the 1/48 Peddinghaus sheet.
HTH, Rob