Creating Sustainable and 1960's Inspired Fashion

For years, I have been interested in fashion history, and I have primarily focused on fashion from the 1960s’ due to the cultural impact of the time period and the music and art scene. However, it has proven to be a struggle to find genuine vintage that fits me well, is in good condition, and is reasonably priced. (Especially in New York.) While brands such as ModCloth can provide recreations of vintage clothing for a more reasonable price, many of these companies do not value sustainably and their clothes are not ethically created. This is something that I value whenever I purchase garments for myself, so it is a struggle to dress in a style reminiscent of the 1960's while also staying sustainable and cost-effective. 

How can I recreate fashions from the 60’s while staying cost efficient and sustainable?