Allyn Scura offers authentic vintage and antique eyewear online (these are not reproductions but never-worn old stock!). All prices are in US dollars and they ship anywhere in the world using US Postal Global Priority and Express. RetroSpecs is a UK-based site that ships to the US (and it appears that they are willing to ship internationally). Designboom also offers one-of-a-kind vintage Alain Mikli shades.
Buying vintage glasses requires some care. Plastic frames can become brittle with age. There is a risk that frames could be broken when putting in new prescription lenses (most reputable dealers offer a warranty, though you might choose to not risk your _one-of-a-kind_ pieces). Plastic and rubber nose pads can become discoloured with exposure to skin oils and to sunlight. Vintage frames aren’t for everybody, but they shure look great.