Hi, you might have trouble selling such a small quantity unless you find a cartridge collector who is interested. To get a cartridge collector interested, they'll want to know the manufacturer, headstamp, soft point or full metal jacket, and also probably request a photo.
As shooting ammo, .351 WSL can sell from 75 cents to $1.50 each. If you don't get any takers here, try gunbroker.com or auctionarms.com - they receive lots more traffic.