How do I find out what an old sewing machine is worth.

What type and brand of sewing machine is it that you have?

Your public library has books on collectibles and antiques, plus values. If your library does not own a book that has this machine in it (each library doesn't own every book in the world), a reference librarian can find out which library has the info you need and have that info faxed over. Often these books have photos, so you should be able to figure out which is your machine. Be sure to take to the library as much info about the machine as you can find out as to year and brand and model.

Of course that's true about a public library being a resource. However, depending on what the type and brand of machine that it is, it may be possible to come up with an answer on this site so that this site will also be a resource that people can use. That is why this site exists. We get a lot of questions about antique sewing machines here.