Jurgen Voigt requires you to open an account. This involves giving them your business information, but when I did this I just made up a name and gave them my SSN, since a Sole Proprietorship is not assigned a TIN in the US, but files taxes using the SSN. It took me like ten minutes to figure this out. I have ordered from them ever since.
WARNING: Keep in mind that if you choose to use PayPal for any overseas transactions that PAYPAL CREDIT is not set up to perform currency conversion. If you have to pay in another currency you must use regular PayPal, meaning you have to have money for the transaction in your account and cannot use credit.
I have found that using PayPal when buying from Miraphone, Melton, Meinlshcmidt, and Martin Seibold (and it is
Minibal with just one "L" at the end — it is a brand name), etc. is faster and more reliable than using a credit or debit card internationally. Knowing this, Miraphone makes all quotes in the customer's currency, and the payment is converted by PayPal as a part of the transaction at no charge. Jurgen Voigt does not currently quote in Dollars, so you have to do the conversion yourself, I think. But PayPal might do the conversion on either end nowadays, so it may not be an issue. Just give it a try to see how it will work out for you. Sometimes procedures change without any notice, but it always ends up working out, since everyone wants to take your money, heh, heh, heh…
Smaller businesses like Martin Seibold or Jurgen Voigt are not as fast to adopt ways to ease purchases from overseas, as they really make their money as component suppliers to large makers. Your purchase, no matter how large it seems to you, will never get the attention that a standing order for 1,000 rotary valves every month for several years. I have found that the more you order from these smaller companies the faster the person who deals with online orders or emails comes to know you as a customer, and your service and attention improve over time. Orders to a large company that makes horns frequently go unanswered if you want a few parts as that is not really what they do. Order some slide tubing from Melton and see how that goes; it is hit or miss, depending on a lot of things.
Some companies have discovered the FrankenTuba movement and have upped their game to fill small orders to small businesses or even to individuals, though few have come out with a component catalog and price list. Miraphone is WONDERFUL to work with, but getting the right part is an exercise in annotating photos, emailing back and forth, and improving your ability to communicate clearly in very basic German and very limited English. And you have to learn what each company calls certain parts.
(Jake did a great podcast on this, demonstrating that the regional dialects of German have caused each major maker and component supplier to develop names separately, to the point that sometimes they mess up orders between them because a common part name is used for different parts in each shop, so a box of X widgets is shipped when Y widgets were ordered. It is a linguistic misadventure. The biggest discrepancies seem to be between Bavarian and North German makers.)
Miraphone, for instance, will sell you anything they make. If it is not currently in stock they will make it for you special. If you need custom work or specific measurements for rods or tubes they will do that, too, for a reasonable shop charge. I have even had them send something out for engraving since it was for a restoration and they no longer employ engravers. They delivered it across town to an engraver they know and trust, the work was done, he was paid by Miraphone, and they tacked that onto the price and shipped it out. It was beautiful work, too. This was not cheap, but Miraphone wants to sell stuff, and they are not boxed in with the attitude that they make and sell instruments. They understand that there is a growing interest in doing work for oneself and that components need to be sourced, so they are working to make components available. Unfortunately, there is no printed (or online) catalog of components used to make their horns, and no listing of services they are willing to do; every order is a one-off and you have to set up everything yourself. It is very much worth it, but the process is still quite cumbersome. I have made it my habit to request part numbers for certain things BEFORE I place an order. I add them to my ever-expanding catalog of Miraphone parts and I update the prices as I order things. (They increase a small amount every quarter.) Now I can re-order parts I use regularly by using their in-house part number, which is MUCH EASIER.) In doing this I have even learned how parts of their numbering system work, like decoding a car's VIN. Now I can order some things intuitively, by asking whether there is a part with XXXXX number and whether it fits a specific description. If so, then I use the number I ginned up myself using their system et voila! I have the needed part.
Getting parts from overseas suppliers is a part of owning a repair shop. It can be a PITA because there is no method to it other than trial and error. If you order stuff a lot, you learn. If you don't, you come here and ask questions. Some of us are unwilling to share hard-won information and some (most) will steer you to the correct place or at least give you hints. Joe is a great source. Dan is, too. And obviously, "professional secret" means nothing to me.
The most important thing to remember when buying from Germany or elsewhere is that you be patient, write as simply as you can, take very clear photos, and annotate them with arrows or circles to show *exactly* what you want. Learn to take and read measurements in metric, and be as polite as you can. Do not be obsequious: this is their job and it is your money. Just clearly state your request or requirement. These are not Americans, and many things we normally do in business conversations baffle them. Don't ask them how they are or have been, even if you know them from years of ordering. Just say hello and goodbye or you might be getting laughed at in their shop. "Why do they want to know how my life is going? We are not personal friends? Why do they care? It is creepy." HAHAHA!!!
Best of luck!