I think it's easier to sell old quilting magazines here than on eBay. Here you don't have fees, and you have an audience that is interested in quilting. However, you do need to make enough posts to qualify to place an ad here.
Are you familiar with eBay? If you have an account there, you can sign in and then search for your type of magazines, checking "completed listings" to see what they actually have sold for. (What people ask and what items actually sell for can be dramatically different.) I would do this kind of research on eBay before offering the mags for sale here, and I would probably offer them for a little less here since there are no fees you have to pay.