I am as interested as you are. And I only live seven hours by train from Cologne. As a sales outfit Farina have gone practically down. Nothing much we can do, I am afraid. I believe they are still a family outfit, and the living heir(s) are not very active. After a moth of trying to contact them I found out that you can order things from them in Cologne. They say they ship world wide but they didn't indicate what shipping costs would amount to. The Museum, I hear is operational, and that's where I also heard bottles can still be bought. Stores in Germany do not seem to carry Farina any more. The strange thing is - nobody tells you why!
A total myth is a product I found in Switzerland: Farina am Dom, Cologne. It also says 'Original Eau de Cologne' and smells similar to 4711, for less even, (no Tulip). I wonder if it's from the same house for half price, sold in common chain stores. The bottle reminds of 4711 and does not come in a box. 'Original Eau de Cologne' is a registered trademark.
I bought Roger & Gallet's EDC 'Extra Vieille, 1806' (the BN directory makes two different colognes of the same, I believe). Without being able to compare it to the white label / red tulip Farina, I have no doubts that this is as close to the original formula as you can get nowadays. It smells best, very natural, and it lasts much better than 4711. Imagine something between 4711 and Acqua di Parma, Colonia (not the Colonia Assoluta which is more powdery, and also contains lasting rose water). I am very happy with R&G Extra Vielle! It must not be forgotten that those colognes were not made to give you a lasting scent (hence: 'water'), and Napoleon used them not to replace his violet perfume. He and his officers used them to freshen up, to clean a wound, or perhaps to get rid of BO.