hi there! i just wanted to respond with a website and a couple of ideas... http://store.purlsoho.com/purl
purl has an awesome selection of high quality yarns available online... whats cool about their site is that you can search by brand, fiber, or gauge. they have all of the typical animal fibers, but they also have yarns made from polyester & nylon, silk, linen, and bamboo. i'm assuming the nylon/poly blends are somewhat similar to acrylic... but i bet the ones on the site are much nicer than what you would get at your typical craft store. and the silk, of course, would be an idea only if you weren't concerned about the silk worms. (i do know some vegans who won't eat honey, etc etc). a lot of it is quite expensive, but even if you don't end up buying from them it is fun to look and drool! and maybe this will give you a couple of ideas for other options you have.
i knit with wool mainly, but i am vegeterian so i can see where you are coming from. i don't believe that using animal fibers is cruel, but i also understand that being vegeterian or vegan is a personal choice that is no one's business but your own... so you should do what you personally feel comfortable with. i know i hate it when people are critical about my eating habits and the fact that i won't buy anything made of suede/leather/etc... but i know that i am happy with my lifestyle and would have it no other way. so yeah! three cheers to you for doing what you believe is right!