In almost all cases, it is cheaper to buy a ticket to HNL, and then
separately buy your inter-island tickets (and do NOT do it through CO).
HA has some deeply discounted fares for $49.99 + $2.75 fees O/W (or whatever) for some flights. You cant do better than that. Go to
www.hawaiianair.com to view and book. They also sell inter-island coupons for about $54-$64 O/W as do all the TA in Hawaii. You can also buy the coupons through the Bank of Hawaii ATM machines in the HNL airport or elsewhere. Aloha Airlines is OK. No CO miles though.
Some other deals are on the HA site. Search around and save. Good luck and enjoy the nice islands.
MisterNice