You can search them in the web broswer, like google with key words "vintage glasses frames". Then you will find many online optical stores selling vintage glasses frames will be listed. I know one called House of Sunglasses which offer affordable vintage glasses.You can go to have a look. Good luck!
You can get your vintage glasses frames from many online optical stores. One of them is Framesdirect which provides Vintage style glasses. They have Virtual Try-On System, so you can try the glasses on to find one that suits you best. Another one is Firmoo.com which also have vintage glasses frames sold. Theyr have Virtual Try-On System, too. I ever got a pair of vintage glasses from them and it suits me fine.
I like vintage glasses too. https://www.vintageeyeglassesonline.com/ you can have a look on this website. But before placing an order online, you'd better have a try in an optical shop. If this kind of glasses doesn't fit for your face shape, you'd better choose another kind of style. Good luck!