The Philippi headwear collection is currently the world’s largest
collection of clerical, ecclesiastical and religious head coverings
and is unique in both its scope and size. You will find examples of headgear from every religious persuasion around the globe, whether ceremonial or worn as part of everyday life. In addition, the collection includes 116 religious objects.
In the shop of Zakład Krawiecki Fides, they sell these kaszkiety. The vendor told me that he sells a lot of them to the Polish clergy. By the way: They have a wide range of cassocks and make them to order, too.
Or get your "Częstochowaian" kaszkiet directly from: