The two-ply jumper weight that she uses is just like this:
It's considered a fingering weight yarn. I used the Jameison Smith for my sweaters and the colors are just so beautiful! It doesn't feel soft the way many yarns do, but it's not supposed to. The sweaters feel nice, though, and look as good as when I made them.
If the price isn't what you're looking for, Knit Picks has some that would work. It doesn't have the heathered look of the J&S.
I don't think the Starmore yarn is available anymore but it might be worth a Google.