I recently brought an entire set on tf2outpost.com. I brought of them 7 for 1 scrap each from individual traders, and then decided to quickly finish my collection and easily got the last two for 2 scrap each.

If you are willing to be patient, at least for the moment, you can get all the haunted souls for 1 scrap each. Upvoting.

These still fetch 1 reclaimed with some time.