This is a gold mine.
The Vintage Patterns Wikia has out-of print patterns from the 1900s-1970s available online.
Let me repeat that. Sewing patterns from the 1900s-1970s. Out of print. Online. For sale from vendors.
Here’s what the site says about what they’re doing:
We are working to create one location online where people can go to browse through vintage patterns starting from the year 1992 and older and share information about them.
The vendors include names we know, including Butterick, McCalls, Vogue, and Simplicity. But it also includes vendors long out of print before I began sewing, like Advance, Hollywood, and DuBarry.
This is an absolute treasure trove for anyone interested in making vintage wear. Not all of the patterns are available… but one can dream.