That's not true at all. In another comment of mine I discussed this. They generally get their equipment outside of the community. They are no longer self sufficient in the sense that you think they are. They might make some shit but for sure go to Costco and stuff like that. The costco close to where I live even has a place for their horse and buggies(which should be outlawed IMO. The cruelty to horses is undeniable and the Amish don't even pay road taxes).
You have a big misconception about Amish. They are not minimalists in any sense of the word. Don't let the button thing fool you. They're just a shitty cult at this point.