Hi Nishit,
It looks like this might be due to a tiny typo that sneaked into our documentation, the correct URL for the Get a single Price List Item endpoint is /v2/price_list_items/:id.
Thanks a lot for flagging this, we’ll get it updated in our docs right away 
As for your other question regarding the creation of price list items, I’ve now replied to your original thread regarding this here.
Best wishes,
Ewa