Buying new battery in Hawaii/ Core Credit

2006 Prius
120,000 miles

Hello!
Does anyone live in Hawaii and had to replace their HV battery? I'm just wondering how much you had to pay. I was quoted $3650 for the battery alone (new), it seems a bit high to me but I know that shipping a battery to Hawaii cost extra $$$. I took my Prius to my regular auto mechanic who told me that the whole battery needs to be replaced, he said that because of shipping restrictions to Hawaii it would be hard to have a battery shipped over. He called the local Toyota dealership and they said they have 7 prius batteries in stock and the price would be $3650. I called another mechanic who specializes in hybrids, he told me he would like to run a dianostic test first, to see if the whole battery would need to be replaced or just certain "cells". The diagnositc test alone would be $400-$475. I know it would be cheaper to have only certain cells replaced but I would rather just put in a new battery. Also, I've been reading on certain forums that there is something called a "CORE CREDIT" where Toyota gives back a certin amount of $ for the old prius battery to be recycled. When I asked the first auto mechanic about this he didnt know anything about it.

Comments and advice from anyone that lives in Hawaii and had to deal with this would be much appreciated or anyone in general that has advice would also be much appreciated! Thank you!