Does anyone have a source for traditional suspender hardware - particularly the adjusters that brands like Albert Thurston or Brooks Brothers would use for their braces?
I have searched high and low and all I can find are these fairly cheap ratchet adjusters: https://www.etsy.com/ca/listing/227691321/50-sew-on-ratchet-slide-adjusters-1?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=metal+adjuster+clips+garter&ref=sr_gallery-1-7&search_preloaded_img=1&organic_search_click=1
I would recommend checking out the aptly named Suspender Store:
https://www.suspenderstore.com/Shop-By-Suspender-Styles/
I am not sure if they will sell just hardware or if they will only sell completed suspenders. If they won't sell just the hardware, you could always order a pair and harvest the parts you need to make your own.
I have never ordered from them, but they are based about an hour away from my home here in Maryland, USA. Family owned business that's been around for I think over 20 years.