I pick up my vintage fabrics from local antique estate sellers - they are wonderful at telling me dates/provenance of fabrics. I have some amazing 30's fabrics I bought recently.
Etsy has a lot of nice bundles.
there are a ton of reproductions out there so make sure you use a trusted/knowledgeable seller. :-)
good luck with your hunt! I'm looking for a few specific ones myself (I've posted them here).