Never from Aululani, but I do have a Mother In Law on Oahu and I am pretty sure she has mentioned that the flat rate shipping is about double what it is on the main land. I can't remember exactly. I'm usually shipping TO Hawaii.
Shipping to Hawaii isn't so bad if you use the USPS flat rate boxes. Just don't let them try to charge you an international fee. (Sadly yes there are many out there that don't realize Hawaii is a state not a country)