I too can't use wool. I don't even like to work with it for someone else's gift. Angora and fluffy fibered yarns bother my contacts, so they are out too. Some acrylics even make me itch! But I do LOVE cotton! Here is a link to some fabulous varigated colors in a great 100% cotton yarn - and only $2.25 a skein is a steal:
Elann.com has some fantastic bargains and lots of free patterns.
I also love Red Heart Casual Cotn Blend. It is all varigateds. It has enough cotton in it that I am not bothered by the acrylic. Herrscners and Joann's sell it among others. It is a little pricey - but the skeins are large.