lets you search for yarns they carry by gauge, and also by yarns that felt. Kureyon's normal gauge looks to be 4.5 sts/inch.
I don't know of any yarns off hand that compare to Kureyon's gorgeous color and variegation. If you don't mind using solid-color yarns, KnitPick's own "Wool of the Andes
" yarn, which is only $1.79/skein (!), knits up at the 4.5 gauge, and should felt well. In fact, I just ordered a bunch of this yarn to make a felted knitting bag, based on the booga bag! I got my yarn in the mail this weekend, and it looks like great yarn! The colors shown on the site were quite accurate.
Hope that helps!