My db killers cost me £50. A little bit pricey but they are tailor-made for my exhaust and fit nicely.
It's hard to tell from the photo in the ebay ad what you're actually getting. The circular "plugging" disc is at the opposite end to my Scorpion db killers' and there are no small holes along the length of the killers in the photo. It's also hard to tell if the "inlet" end of the db killers is closed off or not. For the price, though, it might be worth a try. If they don't fit your Scorp's, you could always sell them.