Congratulations on starting to sell - itís an exciting step!
To your question - luckily you can buy small quantities of Dorinia SA E at Hekserij, which is where I get mine. Unfortunately to buy direct from Firmenich you need to be buying by the truck load (or at least the pallet of 25 kilo drums)!
There is also a yahoo group where some of us sometimes do group buys of things that are hard to buy in sensible quantities that you might want to investigate as well.
Security of supply of some of these things is a worry you are not alone in experiencing I assure you.