I count myself lucky to have found four decent cashmere v-necks.  One from Paul Stuart in maroon, one from Brooks in navy blue, two from Alan Paine before they became crappy: one in navy, the other in grey.  I love pulling on the Paul Stuart with a white Brooks button-down and rumpled chinos to go food shopping.
Now, try and find a really good cashmere crewneck (I've not yet looked for a cardigan).  As Conrad had it - The Horror!  The Horror! 

I'll have to start thinking Zegna or Brioni.  Once I start making money again. 

You'll see this Chinese-made cashmere doing the rounds.  Don't be tempted.  A decent merino or lambswool jumper will be much better value.