Where is the best shorter cheaper way to go to Jiuzhaigou from Chengdu?

,as i understand that i must book group trip there as a woman 61 years old and alone :) .. So my question is :could it be 2 or 3 days trip only ?
do i need one day to see every thing inside the park ? or to visit more than one day ?
if you know prices from Chengdu ?
Thank you