Online prices are increasing. Not suprising given the fact that FDCs are probably much rarer than normal stamps. The numbers I got from the Austrian stamp service reach from 2500 in total (less than 2%) to ~1/10th (10%).
Do you have a breakdown on the amount there are each separate color?
Would love to know the amount of Reds and Yellows out there on a FDC. Or how many FDC sets can be made.
This is pretty hard to say Krogo. I tried to get this info so badly, but nobody knows.. not even the Austrian Post Collectors Society.
I just know, there are two different types of FDCs
PLUS - and this is really interesting - there are some very rare special editions. (signed by the artist, special editions for some collectors)
I dig deeper and let you guys know, when I get more info!