Midwest gunworks has those lanyard pins for about 5 bucks
Smith & Wesson J-Frame Lanyard Loop Pin: MGW
Shipping is probably more than the cost of the part. You can probably make 40 of them out of one free hanger. It's plenty strong and virtually indistinguishable without removing it and looking really close. Besides, I can't imagine may folks actually attach a lanyard to their gun.
Have you tried contacting Smith & Wesson about getting a replacement lanyard pin? They are usually pretty good with sending out stuff like that in my experience.