I pay 10 cents or three for a quarter at a thrift show, but mostly I get them for free when people donate them to the Friends of the Library and they put them on the free shelf in the library lobby.
I did pay more than a couple of dollars for one once when I was missing one issue to make a quilt that was serialized in Australian Patchwork and Quilting (a really fabulous quilt and a wedding gift for step-son and wife,) so it was worth it.