Here is another source to check for recessed soap dishes: Deabath.com, which has maintains a rotating selection of both of New Old Stock and salvaged ceramic tile accessories on their website. Above: A Hall-Mack “Chinavogue” soap dish from 1958, still in its original box. Gosh, I want to get all gushy about how beautiful this is… Deabath.com — aka Bathroom Machineries — also has ceramic tile-in toothbrush holders, toilet paper roll holders and shelves… not only in white, but also in a catch-as-catch-can variety of vintage colors.
Recessed soap dishes are a pretty popular topic. I now have a list of several places to find them, along with other recessed and tile-in ceramic accessories — including both vintage New Old Stock (NOS) and made-new: