Some of the rarer yarns out there, I am sure nifty knitters already know all about that.
Qiviut yarn gathered from the soft underbelly of the Musk Ox. I hear it is collected only once a year and sent to Eskimo women to knit into garments for sale. Costs about USD$80 for 25gm.
Vicuna yarn is gathered from the rare alpine creature once every few years because that's how long it takes to grow back. This active creature is usually wild as it escapes captivity easily. Soft and luxurious, it is a rare material that costs USD$300 for just 25gms and is said to be worn by royals. Available only in its natural brown colour as it does not take to dyes or chemical treatments.
100% Yak Yarn costs USD$25 for 50gm and is fast replacing cashmere as the new luxury fibre. Known for its strength and warmth, it is also purportedly odour resistant and moisture wicking (anti-static).
Camel Yarn is another alternative to cashmere, it consists of the soft fur underneath a camel's coarser outer layer and the younger the camel the softer the yarn. Woven into a shawl, it is lightweight and soft while still able to keep you warm. Prized for its inability to felt as easily as other types of yarn. Baby camel yarns costs just USD$20 for 50gm, it is cheaper but more difficult to obtain.
Mink yarns are the new alternative to mink fur as the animals don't have to be pelted to make the clothes, minks just get a haircut a few times a year to make mink yarn that is then knitted into clothes and accessories. USD$25 for 50gms, its cheaper too but looks less pouffy.
Vegetable yarns have a lovely sheen like this Sugarcane Yarn shown here that I have yet to obtain. It's similar in lustre to Soybean Yarns and Milk Protein yarns. It is manufactured in a similar manner to Bamboo Yarn that is even shinier. I have a real love affair with vegetable based yarns. Did I mention how soft these are, USD$15 for 100gms.
SeaCell® Yarn is derived from seaweed and is usually blended with silk to create a yarn worthy of any mermaid. Apart from being soft and suitable for sensitive skin, it is also anti-microbial and able to absorb moisture effectively. Silk blended SeaCell® yarn retails at USD$18 for 50gms.