GGH Kid is a worsted weight mostly mohair yarn that's fuzzy. Be aware that mohair gives you that fuzzy, soft, fluffy look and using another yarn it may look different. If you don't mind a little different look you could use almost any yarn that gives you about 18 sts over 4 inches on the gauge.
When asking questions ALWAYS post the name and a link for the pattern if you have it.
FYI, I was googling to find out the same thing and came upon your thread. I just found a specific yarn that looks like it might work. On the knitpicks site, they have a worsted weight alpaca nylon blend that looks like it might give the same effect. The name of the yarn is Reverie.
Thanks for the link, Jan. I think that it would even make up nicely in a soft acrylic yarn which might be handy if you want something you can machine wash and dry in the dryer and soft acrylics get fuzzy fast if you like the fuzzy look. It looks like a fun knit.