Have you considered buying them from a German based reseller, such as https://www.lokmuseum.co...ine_shop.php?suchen=7558 ?

Another question: Why reed? There are other more reliable solutions for train detection. Are you using C, K or M tracks? I’m sure you will get some good advise on this forum.

There are three kinds of feedback mechanisms possible with Marklin. The Contact Track is the most common and uses the fact that the wheels of ac cars and locos are conductive. The main advantage is that a signal is sent to the controller as long as there are conductive wheels on the track. The Circuit Track is the easiest but requires a slider to activate it. The main advantage is that it can identify which direction the slider is going. Finally there is Reed Switch whose main advantage is being able to have specific trains identified. The main disadvantage is the magnets are attracted by the tracks. I bought the magnets on ebay but most retailers in the U.S. had them.

I replaced all of my Maerklin magnets with neodymium magnets available at Michaels in North America. They are much stronger and come in different sizes. I found the Maerklin magnets to not be as reliable for consistent activation of the reed switches.

The problem I have with the magnets is that they pull up the point mechanisms on the old style K track 3 way switches, causing shorts and power shut down. So little by little I have converted most of the layout to contact track sensing. Very consistent activation, but you better get the location right on the first try on a permanent layout.

I learned that M and Z track metal turnouts often pull the strong Nd magnets from the loc. I resorted to gluing magnets for Z layout operation and no reed switches for M layout. (No experience with C and K track)