I dont think that is the stock resonator either, IIRC, I believe on the stock one it's side in, same side out (to make it fit where its supposed to go). But those pipes definately look stock with the crimp bends.
$100? I dont know, its almost impossible to tell what kind of life is left in the muffler or resonator, and you may end up spending $100 only to have to replace both those things in 6months or even less. Also, what does the Cat look like inside? is it all melted looking or have alot of buildup in the honeycomb? if its in reasonably good shape, and you HAVE TO HAVE a cat for where you live, then I would say it might be a worthwhile deal.