I can’t find Ryans post to reply to where he was asking about where to get 19th century clothing.
www.saddlerywarehouse.co.nz has formal riding clothing (top hats and tails) the website blows but the warehouse is very big with lots of stuff.
Try wedding suit hire places and see what they do with stuff when it wears out/gets ripped etc.
If you have some money to spend, you can get brand new ones for US$100 online. etuxedo.com/tuxedo_packages/pkg_prom.htm