Yarn question - Alpaca / Vicuna

A friend has asked me to knit a fine tie to be tied as a western
style tie. He prefers alpaca or vicuna. I haven’t used these yarns for
something like that and in fact, I haven’t even seen vicuna yarn in person.

Are these suitable for what I would like to make? Should they be
blended with something else instead? I can see they are quite pricey,
and for something small, I’d rather get some info before I buy.