Literally anywhere...facebook has quite a few used barrel saddles for sale pages. I'm embarrassed to admit this but I have bought and sold 4 saddles in the past year all 15.5 or 16" until I found the one I'm riding now. Facebook ads are free too....
I've sold about 4 or 5 saddles over the last couple of years (16 inch) and the longest one has ever been on the "FB Market" is a couple of weeks. Three days was the average. The only one that took me a bit of time was the 15.5, 9 inch gullet, Crown C and that was probably due to the gullet size more than anything.
15.5-16" Barrel Saddles
