Seen the post about selling a straight Jacket and the problem.
I'm in a simiolar boat as I have some stuff like gas masks that I can't use due to size etc. and trying to figure out if there would be possible to find a way to sell for basically the cost of shipping.
I occasionally see people post items for sale on Fetlife.
I was able to find to post on a corset site and get it to a new owner.
Over time I accumulated some items that were not what expected or wrong size if you might be interested message me for more details
Why not try ebay?