whoever told you alpaca did not take dye well must have had a bad experience.
i've been dyeing fiber for over ten years, and alpaca is one of my very favorite fibers to dye. it takes color nicely and evenly.
your best bet is to use acid dyes (the acid you use to set them is vinegar) and expect beautiful colors! if i can help at all, feel free to email me. i've got a link to a dyeing tutorial on my blog, as well.
here's some alpaca eye candy for you!