How do I obtain slats for a king bed?

I mistakenly gave away the slats/rails that were included with my wooden king bedframe. How can I obtain a new set? The frame requires slats, because there are guides along the side that prevent the bed from sitting on the floor inside the frame. I tried the IKEA slats (Sultan Lade), but their midbeam rail appears to be designed only for certain IKEA bed models (and will not fit my frame). Any help would be greatly appreciated. Thanks!