Does anyone know where I can buy a 34.9 mm seatpost, prefer cheapest, alloy single bolt for my new/old fixer upper folder

as last resort I can use a 34mm and shim it, but would like a 34.9 if someone might know where

thank if anyone knows, searched all over web today and if I don't get a lead here I will try Gaerlen or Calhoun

Brompton posts are 31.6 IIRC

the post that came with the folder is an old 34.9 mm steel heavy ass post that has extensive insertion scrapes and rust

I guess another alternative would be to oxalic acid it (get rid of the rust) and get it rechromed, but the scrapes are really bad

any ideas?? thought I would try here first before mechanics forum