Some of the ways that you could find costumes for your film are the following:
1. It would first help to have actors that already look like they belong in the 1970’s. Having the authentic look can help sell the costumes even more.
2. Relying on second- hand/low-budget vintage stores would be the way to go.
3. Go to a Fabric store or some place online and order fabric to create, If there were a piece that couldn’t be find and needed in the film.