For that price it's definitely a knockoff, but it certainly would be convenient to have!

If it were me, I'd order it early enough to arrive for the con, and then try to make it myself as well. That way I could use the knockoff pin for a model, and have a backup in case I didn't get the made one done. (Because I just know me and costumes!)

...Sometimes I fake jewellery with a lot of detail by printing out a picture of it, gluing it to a 3D base and varnishing it the hell on there.